Fast n Furious

Fast n Furious
mechanical engineers can become a mechanic ,software engineers cannot become a software....

Dec 8, 2013

Vehicle Dynamics

Dynamic Suspension Systems



Dynamic Suspension Systems

Active and semi-active suspension systems control the forces generated in an adjustable suspension component such as struts, or shock absorber.  The adjustment of the damping on individual wheels enables optimization of ride characteristics, dynamic handling, pitch control, and roll-over mitigation.

Fully active systems have the ability to bi-directionally adjust the control forces in the adjustable suspension components.  Semi-active systems apply force in only a single direction. 

In addition to improvements in dynamic performance, functions such as variable ride height and platform levelling are easily implemented which are of great benefit in defense applications and public transport. 

 

 

 

 

Active Differential Control

Pi Innovo has worked with  leading automotive differential manufacturers to apply electronic control to wide range of technologies targeted at light and heavy vehicle applications. 

A standard open differential allows each wheel on an axle to rotate at different speeds, such as when negotiating a turn, to avoid tire scrub. The open differential always provides the same torque to each of the two wheels on that axle. While the wheels can rotate at different speeds, they apply the same rotational force, even if one is entirely stationary and the other spinning with no traction.
 

By contrast, a locked differential forces both left and right wheels on the same axle to rotate at the same speed under nearly all circumstances, without regard to traction differences at either wheel. 
Electrically controlled differentials are a mix between an open differential and a locking differential.  They can intelligently switch between fully open and fully locked.  More advanced systems allow proportioning  between the limits of full open and full lock.  This level of control can address traction, vehicle stability and rollover.  Using OpenECU differential manufacturers have been able to improve the stability and mobility of vehicles across a broader range of terrain.

 
Brake Based Stability

 
Conventional anti-lock brake (ABS) systems detect when an individual  wheel stops rotating relative to the ground, due to slip. The systems then momentarily decrease the braking force until traction with the ground is regained.  Conversely traction control systems momentarily apply braking force during acceleration when slip is caused by high drive torque. 

Sophisticated brake based stability control takes ABS and traction control functions into two dimensions. The system can detect excessive vehicle over-steer and under-steer by using integrated inertial sensors and vehicle dynamics software models.  Mitigation of the excessive under-steer or over-steer is performed by applying one or more brake calipers to induce a yaw moment on the vehicle. 

The flexibility of the OpenECU concept allows proven brake based stability algorithms to be implemented in smaller dedicated ECU platforms or integrated into larger ECU platforms controlling complete powertrain or suspension systems.
 

Aerodynamics

When travelling at speed aerodynamic lift can have significantly reduce the down force on each wheel with obvious degradation to stability and traction.  

Our engineers have developed electronic controllers, derived from OpenECU technology to control the deployment of adjustable spoilers that increase down forces when required without raising fuel consumption at lower speeds by increasing  drag. 

This is just one example of the versatility of the OpenECU concept.

Nov 10, 2013

Zircotec's Ceramic Coating

It is a range of ultra high performance plasma-sprayed ceramic coatings to protect components from the effects of fire, heat, wear, abrasion and corrosion.

Our ceramic coating is highly effective when used on engine exhaust system components including exhaust manifolds, exhaust headers, cat boxes, turbochargers and tail pipes, helping to protect sensitive components from the effects of heat. As an exhaust coating they reduce underbonnet temperatures, increase engine performance, help solve engine packaging issues, and improve engine compartment safety. Based on our proprietary ThermoHold® formulation, our ceramic coating range can only be applied by Zircotec. A series of patent applications are in progress (with two now granted) to protect our technology. Our coatings have been proven to:
  • Reduce underbonnet temperatures by up to 50oC (122oF), as independently measured & confirmed by DAMAX Race Engineering;
  • Increase engine performance, eg. a 30oC drop in intake air temperature can deliver a 6% increase in power, or can increase engine efficiency leading to less fuel usage;
  • Extend the life of vulnerable components and thereby enhance engine reliability.

PLASMA-SPRAY PROCESSING

General Plasma Spray Processing - Plasma-spray processing is a relatively specialised high temperature industrial process that utilises an electrically generated plasma to heat and melt the feedstock material. The process is capital intensive and requires significant electrical power. It offers a method of depositing a feedstock material (the material that is being plasma-sprayed) as a solid coating over an underlying target material. It can also be used to produce free standing parts made from just the plasma-sprayed material. Deposits having a thickness from just a few micrometers (µm) up to several millimeters can be produced using a variety of feedstock materials, including metals and ceramics.

The feedstock material is normally presented to the plasma torch in the form of a powder or wire. This feedstock melts rapidly within the plasma torch, where the typical operating temperature is ~10,000oC (18,000oF). It is then propelled as small molten droplets via a carrier gas towards the target material. When the molten droplets contact the target material they flatten, rapidly solidify to form a deposit that remains adhered to the target material. There are a large number of parameters that influence the interaction of the feedstock with the plasma jet and the substrate, and these parameters can lead to wide variations in the final product and product quality. These parameters include feedstock type and composition, feed rate, plasma gas composition and flow rate, energy input, torch geometry, nozzle design, nozzle offset distance, substrate cooling, etc.

The plasma-sprayed deposits consist of a multitude of pancake-like 'splats', formed by flattening of the liquid droplets. As the feedstock powders typically have sizes from micrometers to above 100 micrometers, the splats have thickness in the micrometer range and lateral dimension up to hundreds of micrometers. Small voids occur between the splats thereby trapping either air or the carrier gas whilst the splats cool rapidly leading to quite rapid crystallisation and large grain size. It is also possible for the deposited material to exist in metastable phases due to rapid cooling (i.e. crystalline structures that would normally only occur at very high temperature). Small micro-cracks and regions of incomplete bonding can also occur under certain plasma-spray conditions. The deposited material can therefore have properties that are significantly different from the bulk feedstock materials, eg. lower strength, higher strain thermal and electrical conductivity. By controlling plasma-spray parameters it is possible to control and make use of these changed material properties to suit specific applications. 

This technique is mostly used to produce coatings on structural materials. It can be used to provide protection against high temperatures, corrosion, erosion and wear, or to change the appearance, electrical or tribological properties of the surface. The technique can also be used to replace worn material. Free standing parts in the form of plates, tubes, shells, etc. can be produced. The technique can also be used for powder processing (spheroidisation, homogenisation,modification of chemistry, etc.). In this case, the substrate for deposition is absent and the particles solidify during flight or in a controlled environment such as water.

Nov 9, 2013

Design

Strategy and Design
 Recall from our discussion of operations strategy that product design must be consistent with the overall strategy of the firm. In general, we would expect firms that have a low-cost strategy to have fairly standard products that change very little over time. A firm with a differentiation strategy might have a large variety of products, highly innovative products, or products with many features.
    • Low Cost Strategy
      • Standardized Products
      • Little Change over Time
    • Differentiation Strategy
      • Customized Products
      • Large Product Variety
      • Highly Innovative Products
      • Products with Many Features
It is essential for designers to know the overall strategy of the firm when designing new products. Increasingly firms are using differentiation as a way to compete. We would expect the design function to be extremely important when a differentiation strategy is employed by the firm. Designers must also be aware of basic design principles that allow new products to:
 
Come to market quickly,
At a competitive cost, and
Of high quality
A good design process is essential for excellent product development.
 
The Design Process
The stages of the design process are illustrated in the diagram below:
 

Generally, ideas are generated, then studied for feasibility. If the product is feasible, a preliminary design is generated from performance specifications, and a prototype is built. Process planning and final design are worked out during the next stage, and final design and manufacturing specifications are spelled out. Manufacturing begins when the product and process designs are finalized.
Idea Generation
Ideas come from many sources, including:
    • Customers
    • Competitors
    • Suppliers
    • R & D and Product Development Departments
Some companies label ideas from customers as market-pull and ideas from R & D as technology push. While ideas from customers are thought to be the most important, many products come from internal units specifically designed for product development.
Example: When IBM developed its first portable computer, individuals of exceptional talent were grouped together and sent off-site to develop the new product. Many companies use the "think-tank" approach for new products. Products that are highly technical often require development to begin with technical experts since customers have not yet thought of the product. After product introduction, customer input is essential for product improvement.
Feasibility Study 
 
A feasibility study is an analysis to determine if a market exists for the product, and if so, will financial returns be adequate enough to support the product? Several of the analyses that must be done include:
    •  Market analysis -- assesses the demand for the product through demographic studies, customer surveys, interviews, focus groups, and market tests.
    • Economic analysis -- examines pricing policies for the new product; compares price and cost for the sales volume, and estimates the financial return for the product
    • Technical and strategic analysis -- assesses any new technology needed for the product or process; evaluates the strategic fit of the product with the rest of the firm.

Preliminary Design
 A prototype is built from preliminary designs and performance specifications (instructions of what the product is supposed to do). The complete design process is an iterative process that involves building, testing, changing, testing, etc. Design is concerned with both form and function.
       Form -- the physical appearance of the product
       Function -- the performance of the product
Final Design and Process Planning

 Final design is the stage at which detailed drawings and design specifications (product size, composition, form) are produced. Detailed drawings were called blueprints in the past, but now most detailed drawings are donewith computer-aided design (CAD). If you've ever seen blueprints or CAD drawings, you know that they contain many technical details and instructions that allow anyone working with the product to understand how it is made. Some details of process planning might also be included on the drawings. Process plans indicate which parts are purchased, which machinery must be used, how products are assembled, etc. Manufacturing specifications are detailed instructions for producing the product.
 
Improving the Design Process           
 As we mentioned earlier, more firms are using differentiation to be competitive. Since differentiation often requires uniqueness in the form of exceptional products, good design processes are essential. Poor design processes result in delayed market exposure and poor product quality. One major problem with poor design processes is excessive use of engineering change orders (ECOs). ECOs are documents that detail changes that must be made to a product after final drawings have been released. They are expensive and time-consuming.
Example: Manufactured or modular homes are becoming increasingly popular for modest-priced housing. With modular homes, framing, floors, windows, doors, and walls are constructed and assembled in a factory, then transported to a homesite. The foundations, and sometimes roofs, are made at the homesite. Suppose a window was designed into the middle of a bedroom wall, but the customer notices that he will have more room for furniture if the window is placed off-center. Changing the location of the window will require an ECO -- which means changes on the architectural drawings, rework of the existing window, scrapping of existing framing, etc. Delivery of the home may be delayed, and workmanship may suffer if workers rush to make the change.

Improving Design Processes
    • Using multi-functional design teams
    • Using concurrent engineering for product and process planning
    • Design for manufacture (DFM) and design for assembly (DFA)
    • Design for the environment
    • Measuring design process quality
    • Using quality function deployment (QFD)
    • Designing for robustness

Design Teams
Design teams composed of marketing, manufacturing, and engineering are necessary for getting timely information from all relevant decision areas. Others who may be useful team members include customers, suppliers, dealers, lawyers, and accountants. Cross-functional teams are some of the most effective since each function has information unique to its own discipline. There is less danger that one person will duplicate another's work when cross-functional teams are used. Furthermore, early communication about particular functional needs allow for early planning to cover each detail.
 
Concurrent Design
Not so long ago, manufacturers used to talk about engineers "throwing the drawings over the wall" to manufacturing. This phrase was used in reference to the fact that engineers and manufacturers did not communicate about products very well. Engineers may have specified parts or production processes that were not available or were difficult to obtain. It was manufacturing's role to accomplish monumental feats of production without complaining. Today, we recognize that such failure to communicate is bad business.  Concurrent engineering requires early manufacturing involvement or continuous manufacturing involvement.
Design for Manufacture
In recent years, more attention has been paid to technical methods of design improvement. Some important technical concepts are:
Design for manufacture (DFM) -- designing a product so it can be produced easily and economically.
Product simplification -- designing products using a minimum number of parts and simplest manufacturing processes.
Standardization -- using interchangeable parts on multiple products so that some parts can be manufactured in high volumes for economies of scale.
Modular design -- combining standardized building blocks, or modules, in a variety of ways to create unique finished products. Modular design can also mean building a few common "platforms," then adding different features to make customized products. It is a method of gaining the benefits of low cost standardized parts without losing the design flexibility that allows customers to choose their options.
Design for assembly (DFA) -- a set of procedures for reducing the number of parts in an assembly, evaluating methods for assembly, and determining an assembly sequence.
The figure below shows a good example of design for manufacture.


Example: Whirlpool is known for its excellent international products strategy. Appliances around the world differ substantially. Not only are there differences in size and aesthetic appearance, but technical requirements also differ dramatically. Electrical voltages and environmental requirements in each country make appliance design quite complicated. Yet Whirlpool was successful in finding those parts of appliances that are common across a number of countries and using them as platforms on which to add country-specific features. By using such a design strategy, Whirlpool is able to source its high volume parts at low cost from the best manufacturers in the world while using local manufacturers for its more unique parts.
 
Design for Environment (DFE)
 Around the world (and particularly in Europe), concern for the environment is growing. New standards are being developed so that products can be designed to reduce their burden on the environment. Some design guidelines include:
    • Reduce packaging
    • Design for recyclability
    • Design for re-use
    • Design for easy repair
    • Use recycled materials
    • Minimize the use of materials
ISO standards for environmental design are listed under ISO 14000.
 
Measures of Design Quality
When we speak about quality in this section, we are not talking about product quality. We are concerned about how well a design group has followed the principles we have discussed so far when designing a product. If a group is interested in measuring how well it is following good design principles, it should measure things like:
    • Number of component parts and product options
    • Percentage of standard parts
    • Use of existing manufacturing processes
    • Cost of first production run
    • First-year cost of field service and repair
    • Total product cost
    • Total product sales
    • Sustainable development (a measure of design for environment)
Setting good design goals and measuring them is one way to ensure that design groups will seriously pursue better ways of designing products.
Quality Function Deployment (QFD)
 We've discussed the importance of communications when new products are developed. One method of guaranteeing communication among departments, suppliers, and customers is to use quality function deployment (QFD). QFD offers a structured approach for matching customer requirements with technical requirements at every stage of the design and manufacturing process. QFD uses a tool called a house of quality. The Figure below shows the parts of a house of quality.
 
 

On the left-hand side of the house, marketing would determine the essential characteristics of a product important to a customer. The "voice of the customer" drives QFD. Just below the roof, the engineers and designers would list the technical requirements of the product (related to customer needs) they typically design and specify. On the far right, the design group's product is assessed against competitors' products. The center portion of the house shows the relationship between the customer needs and technical requirements, while the roof shows how each technical requirement is related to another. The important analytical portion of the house is at the bottom. Here, the data from the other parts is analyzed for cost and technical difficulty, then rated for customer importance. Where there is a gap between what the customer sees as important and where our design group's competitive assessment is low, there should be changes made. An example of a completed house of quality is illustrated below.
The house of quality actually begins a communications chain that relates requirements for the final product to a series of requirements throughout the design and production process. Product characteristics for the final product become the customer requirements for the parts suppliers. Part characteristics then become the customer requirements for the process planners, and so on. The Figure below shows the relationships between the house of quality and successive design houses. It should be obvious that this structured approach forces a great deal of thought to be put into each level of design and production.
 


Design for Robustness (Taguchi's Contribution to Quality)
Robust designs are product designs that allow a product to function properly under a wide variety of environmental conditions. For example, an automobile that can as smoothly in Alaska and Arizona as it can in middleAmerica is a robust design. Conditions that cause a product to operate poorly (called noise) can be separated into controllable and uncontrollable factors. From a designer's viewpoint, controllable factors are parameters typically specified by the designer -- like material used, dimensions, and processing requirements. Uncontrollable factors are under the user's control or part of the user's environment -- things like heat, humidity, settings, degree of maintenance provided, etc. The designer's job is to choose values for the controllable factors that react to the possible occurrences of the uncontrollable factors:
Robust Design: Influence of Controllable Factors > Influence of Uncontrollable Factors
 
IN-LINE EXERCISE
     The following factors must be considered when designing refrigerators. Indicate whether each factor is controllable or uncontrollable.
  1. Number of times the door is opened and shut
  2. Number of BTUs of thermal energy extracted by the refrigeration unit
  3. Number of shelves
  4. Amount of food stored in the refrigerator
  5. Size of the storage compartments



Reliability

Reliability -- the probability that a given part or product will perform its intended function for a specified length of time under normal conditions of use. For example, tires are expected to last for 40,000 miles when used on normal terrain. A product or system's reliability is a function of the reliabilities of its component parts and how the parts are arranged. Reliability is one of the most important measures of product quality. Reliability is often expressed as a proportion or percentage, like 90%. A reliability of 90% means that the product will operate as intended for a certain time period 90% of the time.

Let's take a look at how reliability can be used along with design for manufacture, specifically when manufacturing a system.
A system is any product composed of more than one component. Components can be connected to each other in two ways:
    • In series, or in such a way that all components must operate if the product or system is to operate.
      • A fuel tank -- connected to a fuel hose -- connected to a fuel pump -- connected to fuel injectors is a system with components in series.
      • If one of the components in the fuel system fails, the entire system fails to operate.
      • Think of a series system as water flowing through a pipe and series of valves. If one valve closes, the water flow stops.
      • System reliability for series systems is expressed as
R= R1R2R3 . . . Rn, where n = no. of components in the system

Series Reliability


scan0001.jpg



    • In parallel, or in such a way that if one component fails, a similar or identical component will take over its function. Parallel systems are said to be redundant.
      • The space shuttle has redundant computers. If one computers fails, another takes over its function.
      • Think of a parallel system as a pipe that branches off into two pipes with valves in them, then re-joins into a single pipe on the other side of the valves. If one valve closes, water can still flow through the other side.
      • System reliability for parallel systems is expressed as:
Rs = 1 - (1 - R1)(1 - R2). . . (1 - R n),     or  

RP=R1+R2(1-R1)     if only two parallel components are present
Parallel Reliability
scan0002.jpg


Another way to think about computing parallel reliabilities is to reason as in the following example:

Example: If two electrical resistors are installed in parallel, and each has a 90% reliability, that means each resistor will operate 90% of the time. One resistor may fail, and that may occur 10% of the time. During that 10% of the time, the other resistor is likely to work, but only 90% of the time. If we multiply 90% times 10%, we get 0.9, or 9% of the total time that the second resistor will provide backup. This tells us that during the time when the first resistor fails, the second resistor will work 9 out of 10 times. Since failure of the first resistor occurs only 10% of the time, our second resistor covers us 9% of the total time. To summarize, the first resistor covers us 90% of the total time, and the second covers us 9% of the total time, or 90% of the 10% failure time. Adding the reliabilities together, we get 90% for the first resistor and 9% for the second resistor, for a total of 99%. Mathematically, we can say RP=R1+R2(1-R1)


EXAMPLE
We can compute system reliabilities for different systems by reducing each component into its equivalent series reliability. Suppose we have the following system: 
What is the system reliability?
The first step is to reduce the parallel reliabilities into the equivalent series reliability, so we must find the reliability of the RB - Rparallel system:
RBB = 1 - (1 - RB)(1 - RB)
RBB = 1 - (1 - 0.92)(1 - 0.92)
RBB = 1 - (0.08)(0.08)
RBB = 0.9936
The equivalent system is now:
It is now possible to compute the system reliability since all components are at their series equivalents: 
R= RRBBRC
RS = (0.95)(0.9936)(0.99)
R= 0.9345
Suppose we did not have the redundant component at B. Our reliability would be R= (0.95)(0.92)(0.99) = 0.8653. You can see that we improved our system reliability (0.9345) significantly by adding the redundant component B.



IN-LINE EXERCISE

Compute the system reliability for the system below.  First compute the series equivalent for the two parallel systems, then compute the reliability for the entire system.

opsboxes3

Compute these:

opsboxes5
RAA=? RBB=? RCC=?
Then compute RS




Improving Reliability to Reduce Redundancy

Now, we see from the series reliability equation that it makes sense to keep the number of parts in a system as small as possible. As the number of parts in series increases, we increase the probability that one will fail. In some instances, however, system reliability may not be good enough, and the number of parts may have to be increased by putting them in parallel. Note the difference: in the case of parallel parts, we are installing an identical or similar part, not an entirely different part. Still, there are ways to improve reliability while also reducing redundancy:

Boeing747Engine.jpgboeing777.jpgBoeing777Engine.jpgBoeing747.jpg

Example: Boeing is a company that wanted to reduce the number of parts used on the Boeing 777, a  wide-body jet. Its earliest wide-body jet, the Boeing 747 uses 4 engines to support the needs of the aircraft. The engines are installed in parallel so that if one engine fails, the three remaining engines will continue to operate. The Boeing 777 has only two engines -- much larger than those on the Boeing 747. Does that mean that the Boeing 777 is less reliable than the Boeing 747?  No -- each individual Boeing 777 engine is made to be more reliable than each of the four engines on the Boeing 747, so the Boeing 777 is actually more reliable than the Boeing 747. 


Technology in Design
 New product development is increasingly necessary to maintain competitiveness. One tool that has dramatically improved the ability to design new products is the computer.
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Computer-aided design (CAD) is a software system that uses computer graphics to assist in the creation, modification, and analysis of a design. Some features of CAD include:
    • geometric modeling - the use of basic lines, curves, and shapes to generate the geometry and topology of a part 
    • automated drafting - the production of detailed drawings directly from the CAD database  
    • computer-aided engineering (CAE) - simulating operating conditions of a part on the computer and analyzing it for movement, stress, interference, and thermal properties.
    • link to computer-aided manufacturing (CAD/CAM) - the automatic conversion of CAD design data into processing instructions for computer-controlled equipment and the subsequent manufacture of the part as it was designed. 
Benefits of CAD include:
    • reduced lead time for new product introduction
    • quicker product changes
    • quicker product testing
    • real-time access to design information
    • improved design process through better communication
    • more alternatives to be considered
Service Design
We live in a service economy.  The proportion of services in the GDP is large, but not as large as the proportion of labor employed in services.  It is more difficult to find productivity savings in services because of the large labor content.  Service design, therefore must be carefully considered. Service design has some unique characteristics that differentiate it from product design. We will review these, then discuss design concepts for service. 

Characteristics of Service
  1. Services are intangible. Services are experienced; they cannot be touched, felt, or seen. Service design is based on expectations of the experience. Many differences exist for what customers expect for the experience and from the provider.
  2. Services have high customer contact. Customer contact makes production of the service highly visible, unlike production of tangible goods. High visibility means that a positive encounter between the customer and provider is essential. 
  3. Services are perishable. Since services cannot be stored in inventory, service design must define not only what is to be delivered, but also where and when.
  4. Consumers do not separate the service from the delivery (production) of the service. Services are produced and consumed simultaneously. Service design must specify how the service is produced, including :
    • the level of customer participation in the service process
    • front-room (visible) vs. backroom (invisible) tasks
    • role and authority of the service provider
    • the balance of touch vs. tech (level of automation)
  1. Services tend to be decentralized and geographically dispersed. Many small outlets make up most services. Service organizations can become large, often through franchising or "chains," but dispersion means that decision-making and control tends to be more localized.
  2. Services are consumed more often than products, so there are more opportunities for service "moments of truth" (chances to succeed and fail).
  3. Services can be easily emulated, so new service improvements may occur even more rapidly than product improvements 

Concurrent Engineering

CONCURRENT ENGINEERING: WHAT IT IS AND HOW IT WORKS
Automotive suppliers face a number of challenges. Automotive systems are becoming more advanced, while delivery timeframes are increasingly shorter. At the same time, automakers are continually calling on suppliers to reduce costs.
   To satisfy these contradictory requirements, DENSO was one of the first in the industry to adopt concurrent engineering.
   Concurrent engineering works like this: people from a variety of departments, including product planning and production engineering, are brought together in multidisciplinary teams at the start of the product design process. This collaborative approach gives everyone involved equal access to the project's concept, blueprints and objectives. Design parameters are then fine-tuned based on in-depth discussions and parallel decision making within the team, so that remedial actions are taken well before the new product advances to the manufacturing phase. Cost estimates—including everything from personnel expenses to transportation costs—efficiency and quality can also be assessed more accurately to devise the optimum procurement and manufacturing processes. Cost and delivery times are both factored into the manufacturing process during the design phase, allowing us to achieve innovative cost reductions and significantly cut delivery time.
   This differs from the conventional linear approach to manufacturing, where product planning departments create the initial concept, designers use the concept to construct blueprints, and the production engineering department designs a manufacturing process based on these plans. Each of these activities is done independently and without discussion.


The Fruits of Concurrent Engineering
In January 2001, we were asked to design a new type of alternator for the 2002 Toyota Celsior and Estima. The new alternator had two requirements—it had to be more compact, and it had to have a higher power output than its predecessor.
   To increase output, our product design team proposed increasing the number of coils in the alternator. But that led to a number of issues:
  • The limited space available meant that engineers had to use finer wires to increase the number of coils.
  • Due to the higher temperatures resulting from the required increase in power output, the coil wire had to be even more resistant to heat.
  • Existing alternator production line equipment was incapable of manufacturing alternators with more coil windings.
                                                                                 Taking on these challenges, DENSO's material engineers created a new type of high-performance wire that was finer and offered greater heat resistance, while the Machinery and Tools Department successfully developed proprietary manufacturing equipment capable of attaching coils inside components with smaller dimensions. At the same time, our production engineers used simulations to develop the best manufacturing equipment and processes for smaller alternators. These cooperative and concurrent efforts allowed us to meet the customer's requirements: alternator output was boosted to 85 amps from 55, while the diameter of the alternator core was reduced to 128mm from 135. Manufacturing costs were also cut by 30 percent.

 
 
THE BENEFITS: SYSTEMIZATION, MODULARIZATION AND STANDARDIZATION
Concurrent engineering processes do more than just streamline the design and development phases of new product creation; they also lead to smaller and lighter components, systemization and modularization, and standardized components,making us more competitive.
   While compact automotive components help to reduce the size and weight of vehicles and increase cabin space (benefits for our customers and end-users), they help us in our own operations as well. We can cut the amount of materials used; reduce the size of manufacturing equipment; and scale back warehousing. Naturally, this results in a lower cost base.
   Systemization and modularization also benefit both suppliers and automakers. Fewer parts in a component mean materials costs are lower, assembly costs are reduced, and production lines and logistic networks are smaller. In short, we can make products with the same functionality using smaller facilities and less investment. Standardizing components, which entails using common internal devices and systems without sacrificing outward individuality and appearance, allows us to respond to automaker model changes without losing time or resources.
 
 
ENHANCING QUALITY: ADVANCED MANUFACTURING EQUIPMENT AND SKILLS
Quality has to be built into production processes. That is why we trust our highly skilled associates and our highly reliable equipment to achieve the DENSO standard of quality. These are standards other companies find hard to match.
  How do we know? Our consistently strong showing at the WorldSkills Competition, formerly known as the Skill Olympics, is one way. In this competition, skilled technicians from around the world compete in a range of technical challenges that require micron-level accuracy. In the last WorldSkills Competition, DENSO associates participated in five categories, winning medals in all five competitions. In the instrument-making category, DENSO has won the gold medal six years in a row. Because most production lines are highly automated, this kind of expertise is vital in the construction of “mother machines,” core manufacturing equipment employed in our production lines. Designed and manufactured in-house by the Machinery and Tools Department, these machines allow us to make components in unique and innovative ways.
 
 
LOWERING COSTS: AIMING TO ACHIEVE A GLOBAL MINIMUM COST
Since DENSO produced its first component in the 1950s, we have consistently worked to achieve a global minimum cost lower than that set by the customer. This process is even more difficult and demanding as automakers establish competitive global cost bases and automotive component makers face ever-tougher demands to reduce unit costs.
   Concurrent engineering helps us accurately set a global minimum cost—and deliver on it.
   The shared knowledge flowing from concurrent engineering allows each department to provide advice on how best to reduce the final cost of the component: by altering the initial design, adapting manufacturing processes or devising optimal materials, while keeping mid-process changes to an absolute minimum. Aware that most of the cost of a new product is incurred in the initial design phases, we target this stage of the process to deliver cost reductions to our customers.
 
 
REDUCING DELIVERY TIME: INITIATIVES BEGIN AT THE DESIGN STAGE
In the conventional linear approach to manufacturing, delays occurring in one part of the process have an unplanned effect on the rest of the cycle. These incremental delays build up, putting added strain on the production process and leaving less room for maneuver.
   Our unique approach to manufacturing means we avoid this pitfall. At DENSO, “delivery” means more than getting products to customers on time. It is a concept that is factored into every part of the manufacturing process. Multidisciplinary teams cooperate at all phases of the process to devise innovative ways to cut delivery times. Every department plays a crucial role. Working hand-in-hand with automakers, DENSO enhances logistics and inventory control efficiency, and speeds up delivery by carefully reviewing and fine-tuning every part of the process. This way the burden is shared, reducing pressure on the end of the process and helping us to meet tight delivery targets.
 
 
QCD: AT THE HEART OF EFFORTS TO BOOST GLOBAL SHARE
By realizing world-leading levels of QCD performance, we are aiming to enhance customer satisfaction and ultimately increase DENSO's share of the global automotive components market. Put simply, QCD is crucial to a key objective in our current medium-term management plan: capture the leading global share in 23 automotive product categories.


N-Time Technology: Driving Productivity Improvements

N-time technology is a phrase unique to DENSO. It was created to define technologies that drive dramatic improvements in productivity, not easily expressed with ratios. Instead, the word "times" is used. Heat exchange component production lines are a good example of how we have applied this technology to significantly boost manufacturing efficiency. Other benefits include a reduction in production line area and the creation of next-generation components that deliver real improvements in performance. Specifically, we introduced N-time technology soldering
equipment that reaches its optimum operational temperature 4 times faster than earlier devices, speeding up the manufacturing process. Proprietary equipment using N-time technology was also installed at other stages of the production line, resulting in an overall increase in processing and assembly speeds of 2 to 3 times. The combined benefit of all our improvements in the heat exchange component production line was an increase in output of 1.5 times.
 
THE UNIVERSAL PRODUCTION SYSTEM: UNIFORM QCD PERFORMANCE
In building an optimum global manufacturing framework, we have to consider a range of local issues: the needs of automakers, workforce skills, procurement costs, and personnel expenses, to name just a few. Using this information, we rapidly adapt our universal production system to the local business environment and have it up and running with minimal investment. This tried and tested approach means we can quickly achieve uniform QCD performance wherever we operate.
 
 
THE VITAL INGREDIENT: INVESTING IN PEOPLE
No matter how advanced our facilities or materials, people are still the vital ingredient—it is DENSO associates who make the difference. They take to heart our approach to mono-zukuri, our commitment to Quality First, and help us create new manufacturing technologies.
   In April 2001, we established the DENSO E&TS Training Center Corporation in Japan to evaluate skills and provide technical training. This company enhances the skills of two key groups of engineers: those involved in product development and those helping to fabricate the finished products on the factory floor. Building stronger ties between these two groups of engineers ensures that concurrent engineering remains an integral and widely accepted element of DENSO’s corporate culture. The center also supports overseas facilities through training programs designed to foster the skills that our technicians need.


Devising Optimum Equipment and Workflow Processes

Concurrent techniques are not limited to product development processes. We also use them to develop manufacturing equipment.
   On the factory floor, machinery and tools, production engineering and production control departments work closely with engineers, managers and other associates to devise optimum equipment and workflow processes.
   Creating simulated production lines from cardboard is one technique we use. The approach was first employed in Thailand in 2002 to boost productivity and incorporate the expertise and work-related ideas of local personnel. Prior to installing new manufacturing equipment, we build life-size production lines made from cardboard and wood that incorporate mock-ups of the new equipment currently under development. This allows us to simulate and monitor actual workflow processes, helping us to reduce startup lead times. If we notice any potential flaws in the system, we can rapidly make adjustments to fix them. Moreover, we can achieve output targets almost as soon as a new production line comes on stream, helping to further reduce costs.

Jun 30, 2013

Bearings

bearing is a machine element that constrains relative motion between moving parts to only the desired motion. The design of the bearing may, for example, provide for free linear movement of the moving part or for free rotation around a fixed axis; or, it may prevent a motion by controlling the vectors of normal forces that bear on the moving parts. Bearings are classified broadly according to the type of operation, the motions allowed, or to the directions of the loads (forces) applied to the parts.


Parasitic Power Losses in Hydrodynamic Bearings

Parasitic frictional losses in machines result in wasted energy and the generation of heat, which affects the life of materials, including the lubricant. A significant portion of total fluid film bearing losses in high-speed turbomachinery may be consumed simply in feeding oil to the bearings.
At surface speeds below roughly 10,000 ft/min, these extraneous parasitic losses are generally less than 10 percent of those of the oil-film frictional losses. For higher velocities, however, these losses increase rapidly with surface speed and can reach 25 to 50 percent of the total bearing loss in large turbine-generators and related machinery. This article discusses parasitic frictional losses in turbo machinery and suggests means for their reduction.


Sources of Parasitic Losses 
Parasitic losses for both journal and thrust bearings (Figures 1 and 2) can be assigned to two categories: through-flow loss simply caused by the lube oil’s passage through a bearing, and surface drag between the lube oil and rotating surfaces. Due to larger diameter and large surface area, these losses are generally greater in thrust bearings.
Through-flow Loss. These losses result from three sources: acceleration of the oil as it enters feed ports, influx and outflux of lubricant to and from feed grooves, and discharge of the lubricant from the bearing (leakage). Through-flow losses for a pivoted-pad thrust bearing can be assigned to the following sources (Figure 1):
  1. One single velocity head loss for oil entering at the shaft surface velocity. This loss is associated with the flow of the oil feed as it enters under the base ring, makes an abrupt turn, and is brought to the bulk oil velocity between the shaft outside diameter and the inside diameter of the base ring.
  2. One single velocity head loss, calculated at the mean thrust runner diameter, for the oil as it passes into the channels between the tilting pads and into the bearing oil film.
  3. Approximately 25 percent of discharge oil is assumed to be splashed onto the thrust runner to be reaccelerated at the runner’s outside diameter. This action is not typically encountered in conventional journal bearings.

Figure 1. Parasitic Losses in a Pivoted-pad Thrust Bearing
Referring to Figure 2, a plain cylindrical axial-groove journal bearing introduces a total parasitic loss of 1.5 velocity heads (calculated at the shaft surface velocity). This results from acceleration of the feed oil as it enters into the turbulent vortex in the feed groove and then further accelerates as it enters the bearing oil film itself. In pivoted pad journal bearings, on the other hand, vortex action and churning in the square-sided cavity between pads offers more resistance to entering feed oil.
Surface Drag Losses. Power loss from fluid friction drag on wetted shaft and thrust collar areas follows the general turbulent relation for hydraulic drag in channels where frictional loss is related to the dimensionless Reynolds number. For circular annular spaces around a journal, and for overshot internal grooves, as in the upper half of some journal bearings, the estimate of drag coefficient should be increased by 30 to 40 percent These losses would be reduced by appropriate draining of the housing to avoid fully-flooded operation.
Reducing Parasitic Losses
Several strategies may be employed to minimize parasitic losses in high-speed bearings. The simplest is to reduce the oil feed volume. A method that nearly eliminates the through-flow losses in fixed-pad bearings is discussed in the next section. For pivoted shoe bearings, feeding the oil directly to the leading edge of each bearing pad is an attractive method for decreasing parasitic power losses.
Decreased Loss with Partially Filled Grooves.When the oil feed rate drops to the extent that internal grooves in a bearing are not completely filled with oil, the parasitic drag loss in the groove also drops, frequently to a negligible level.

Figure 3. Decrease in Power Loss in a 27-inch
O.D. Tapered Land Thrust Bearing Partially Filled
Figure 3 illustrates this point for a 350-square inch tapered-land steam-turbine thrust bearing operating at 3,600 rpm, wherein a step drop in power loss was encountered with decreasing oil flow. As the design oil feed was gradually reduced, at 166 gpm the total power loss in the bearing dropped from 800 to 473 hp. At this point, the back pressure dropped in the feed grooves with simultaneous elimination of through-flow loss for the entering oil.
Combined with observation of low loss in cavitated hydrodynamic oil films themselves, surface drag losses appear to become negligible for all partially filled zones within a bearing.
Leading Edge Feed Grooves. Several pivoted-pad bearing designs use sprays or channels to feed oil directly to the leading edge of each thrust pad in a bearing cavity otherwise empty of oil. These arrangements avoid essentially all surface drag losses which would otherwise be encountered by rotating surfaces immersed in oil as well as portions of through-flow losses. Such designs are offered primarily for the surface speeds above that encountered in journal bearings with diameters approximately 10 to 12 inches operating at 3,600 rpm. For lower surface velocities, parasitic power losses become so low as not to warrant the extra cost and complexity with specially directed feed.
In high-speed bearings, leading edge oil feed grooves provide significant benefits. Oil flow rates can be as much as 60 percent lower with power loss down 45 percent. While a variety of lubrication flow arrangements, design and operating factors exert an influence, the resulting bearing temperature may be reduced by 16 to 35°F.

Figure 4. Pivoted Pad Thrust Bearing with
Leading Edge Oil Feed Grooves and Oil Lift
Pockets (Courtesy Kingsbury, Inc.)
As a surprising factor, reversing the rotation to place the oil feed groove at the trailing edge of each pad still provides satisfactory operation of a pivoted pad journal bearing at moderate speeds. This suggests that hot oil is still carried over from one pad to the next, and that absence of bulk oil from the bearing cavity is likely the major benefit to be realized from directed lubrication.
As bearing surface speeds range above approximately 10,000 ft./min., significant parasitic power losses may be encountered. At 30,000 ft./min., these losses may range up to half of the total power loss experienced in a bearing – equal to the power loss in the hydrodynamic load-supporting oil film itself. The following are factors to consider for minimizing parasitic frictional losses and achieving lower bearing temperatures:
  1. Limit oil feed rate to the minimum required for reliable bearing operation.
  2. Blend the shape of oil groove entrance ports and groove walls to minimize vortex flow restrictions.
  3. Minimize unessential oil-wetted areas on rotating journal and thrust surfaces.
  4. Minimize splashing of discharge oil onto rotating surfaces.
  5. Utilize directed lubrication with leading edge grooves to feed tilting-pads.