JIGLESS MANUFACTURING PDF

An engineering manager responsible for designing a single part at an automobile company told me recently that the design process mandates steps—not engineering calculations or experiments but workups requiring signatures. When senior managers put most of their efforts into analyzing current production rather than product design, they are monitoring what accounts for only about a third of total manufacturing costs—the window dressing, not the window. Moreover, better product design has shattered old expectations for improving cost through design or redesign. And even greater reductions are coming, owing to new materials and materials-processing techniques.

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An engineering manager responsible for designing a single part at an automobile company told me recently that the design process mandates steps—not engineering calculations or experiments but workups requiring signatures.

When senior managers put most of their efforts into analyzing current production rather than product design, they are monitoring what accounts for only about a third of total manufacturing costs—the window dressing, not the window. Moreover, better product design has shattered old expectations for improving cost through design or redesign.

And even greater reductions are coming, owing to new materials and materials-processing techniques. Direct labor, even lower cost labor, accounts for so little of the total picture that companies still focusing on this factor are misleading themselves not only about improving products but also about how foreign competitors have gained so much advantage.

In short, design is a strategic activity, whether by intention or by default. It influences flexibility of sales strategies, speed of field repair, and efficiency of manufacturing.

I want to focus not on the qualities of products but on development of the processes for making them. Converting a concept into a complex, high-technology product is an involved procedure consisting of many steps of refinement.

The initial idea never quite works as intended or performs as well as desired. So designers make many modifications, including increasingly subtle choices of materials, fasteners, coatings, adhesives, and electronic adjustments. Expensive analyses and experiments may be necessary to verify design choices. In many cases, designers find that the options become more and more difficult; negotiations over technical issues, budgets, and schedules become intense. As the design evolves, the choices become interdependent, taking on the character of an interwoven, historical chain in which later decisions are conditioned by those made previously.

Imagine, then, that a production or manufacturing engineer enters such detailed negotiations late in the game and asks for changes. If the product designers accede to the requests, a large part of the design may simply unravel. Many difficult and pivotal choices will have been made for nothing. Where close calls went one way, they may now go another; new materials analyses and production experiments may be necessary.

Examples of failure abound. One research scientist I know, at a large chemical company, spent a year perfecting a new process—involving, among other things, gases—at laboratory scale.

In the lab the process operated at atmospheric pressure. But when a production engineer was finally called in to scale up the process, he immediately asked for higher pressures. Atmospheric pressure is never used in production when gases are in play because maintaining it requires huge pipes, pumps, and tanks.

Higher pressure reduces the volume of gases and permits the use of smaller equipment. Or consider the manufacturer whose household appliance depended on close tolerances for proper operation.

Edicts from the styling department prevented designs from achieving required tolerances; the designers wanted a particular shape and appearance and would not budge when they were apprised of the problems they caused to manufacturing.

Nor was the machine designed in modules that could be tested before final assembly. The entire product was built from single parts on one long line. No one who understood the problem had enough authority to solve it, and no one with enough authority understood the problem until it was too late. This company is no longer in business. Finally, there was the weapon that depended for its function on an infrared detector, the first of many parts—lenses, mirrors, motors, power supplies, etc.

To save money, the purchasing department switched to a cheaper detector, which caused an increase in final test failures. Since the construction was glue and solder, bad units had to be scrapped. Someone then suggested a redesign of the unit with reversible fasteners to permit disassembly.

But this time more reasonable voices prevailed. Disassembly would not have been advisable because the unit was too complex for field repair. It was a single-use weapon—with a shelf life of five years and a useful life of ten seconds. It simply had to work the first time. Manufacturers can avoid problems like this. One company I know wanted to be able to respond in 24 hours to worldwide orders for its electronic products line—a large variety of features in small-order batches.

Engineers decided to redesign the products in modules, with different features in each module. All the modules are plug compatible, electrically and mechanically.

All versions of each module are identical on the outside where assembly machines handle them. The company can now make up an order for any set of features by selecting the correct modules and assembling them, all of this without any human intervention, from electronic order receipt to the boxing of final assemblies.

In another company, a high-pressure machine for supplying cutting oil to machine tools requires once-a-day cleaning. Designers recently reconfigured the machine so that normal cleanout and ordinary repairs can be accomplished without any tools, thus solving some bothersome union work-rule problems.

There are no guarantees, of course, but the experiences of these companies illustrate how design decisions should be integrated, informed, and balanced, and how important it is to involve manufacturing engineers, repair engineers, purchasing agents, and other knowledgeable people early in the process. The Design Team and Its Task Multifunctional teams are currently the most effective way known to cut through barriers to good design.

Teams can be surprisingly small—as small as 4 members, though 20 members is typical in large projects—and they usually include every specialty in the company.

Top executives should make their support and interest clear. In many Japanese companies, teams like this have been functioning for so long that most of the employees cannot remember another way to design a product. Establishing the team is only the beginning, of course. Teams need a step-by-step procedure that disciplines the discussion and takes members through the decisions that crop up in virtually every design. In traditional design procedures, assembly is one of the last things considered.

My experience suggests that assembly should be considered much earlier. Assembly is inherently integrative. Weaving it into the design process is a powerful way to raise the level of integration in all aspects of product design. Its chief functions include: 1. Determining the character of the product, to see what it is and thus what design and production methods are appropriate. Subjecting the product to a product function analysis, so that all design decisions can be made with full knowledge of how the item is supposed to work and all team members understand it well enough to contribute optimally.

Carrying out a design-for-producibility-and-usability study to determine if these factors can be improved without impairing functioning. This involves creating a suitable assembly sequence, identifying subassemblies, integrating quality control, and designing each part so that its quality is compatible with the assembly method. Recently in these pages, David A. Garvin has analyzed eight fundamental dimensions of product quality; and John R.

I would only reiterate that manufacturing engineers and others should have something to say about how to ensure that the product is field repairable, how skilled users must be to employ it successfully, and whether marketability will be based on model variety or availability of future add-ons. As designers talk with manufacturing or field-service reps, for example, they can make knowledgeable corrections. I know a low-cost source. Product designers and manufacturing engineers used to try to understand these relations by experience and intuition.

Now they have software packages for modeling and designing components to guide them through process choices—software that would have been thought fantastic a generation ago. Managers particularly need to predict reliability, manufacturing costs, and manufacturability. In the past, engineers have dealt with these three issues only after engineering has completed the drawings, the near-final stage in the development cycle. But by then it may be too late.

Two new, integrated, mechanical computer-aided engineering MCAE systems permit engineering teams to test before they build, so they can design for total quality with reliability, performance, and manufacturing costs in mind from the start.

Engineers can vary assumptions about materials, speeds, loads, size, and other operating conditions. In this way, developers can both see the effects of hypothetical stresses and estimate product costs while making design decisions. A company making internal-combustion engines, for example, may use an integrated MCAE system to design reliability and smoothness of operation into the counterbalance for the crankshaft. The system works as follows: a desktop workstation paints an image of a cylinder with all its operating parts on the screen.

The engineer then selects values for counterbalance features like angle, thickness, diameter, etc. As choices are made, the system automatically computes the merits of the design, based on about engineering equations, including compression ratio and stroke. So design variations are tried, evaluated, and discarded with near instantaneous response.

This puts robustness and performance optimization into the very first counter-balance designs. The second new system is an expert system which projects probable production costs for various part or assembly configurations and provides guidance as to their manufacturability. Another parts maker might use this system to project the manufacturability of and costs for, say, its stamped carburetor parts. Each menu holds progressive layers of possible choices.

If the engineer selects metal from the list of materials, the system offers a choice of ferrous or non-ferrous. Under ferrous metals, one can pick from carbon steel, stainless, cast iron, and so on.

There are automatic default values that the engineer might not normally specify, such as surface finish and carbon content. The system also draws on its own data base for manufacturing information like material density and base unit cost. Once the designer completes the menu sequence, the system produces an approximate part cost that includes materials, processing, and tooling expenditures.

Recently I worked on a product containing delicate spinning parts that had to be dynamically balanced to high tolerances. In the original design, partial disassembly of the rotating elements after balancing was necessary before the assembly could be finished, so the final product was rarely well balanced and required a lengthy adjustment procedure. Since total redesign was not feasible, the team analyzed the reassembly procedure solely as it pertained to balance and concluded that designers needed only to tighten various tolerances and reshape mating surfaces.

Simple adjustments were then sufficient to restore balance in the finished product. Another important goal of product function analysis is to reduce the number of parts in a product. The benefits extend to purchasing fewer vendors and transactions , manufacturing fewer operations, material handlings, and handlers , and field service fewer repair parts. When a company first brings discipline to its design process, reductions in parts count are usually easy to make because the old designs are so inefficient.

After catching up, though, hard, creative work is necessary to cut the parts count further. One company I know saved several million dollars a year by eliminating just one subassembly part. The product had three operating states: low, medium, and high.

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Manufacturing by Design

Mokus Offline programming means that the robots are programmed in a computer environment without disturbing the process. Offline programmimg Offline programming means that the robots are programmed in a computer environment without disturbing the process. Maximum manufacturing flexibility also requires the fast creation of programs when the robots weld a new item. Sch of Industrial and Manufacturing Scie. The industrial and scientific breakthrough objectives of the project were:. In particular, DATAFORM aspired to enable rapid, manufzcturing and cost-effective forming of skin panels in aircrafts with digitally adjustable multi-point tooling. The research seeks to develop methodologies, software tools, and to exploit technological manufadturing in robotic and measurement technology to build an environment for enabling jigless assembly of Aerostructures.

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