Engineers use prototypes to reduce costs and to make parts more manufacturable

>One fact of life in the metal stamping and springs industry is that metal components are often the last to be sourced. Since plastic parts cannot be changed without significant mould costs and very long lead times, stamped metal parts and springs frequently need to adjust to other parts' restrictions. This makes prototyping a very important part of the design development process.

>No matter what the industry, each project should begin by establishing lines of communication to get an in-depth understanding of the design, the objectives, and material requirements. A discussion of part dimension tolerance is essential. Some tight tolerances may add significant cost, and may not be critical; others may be achievable at no additional cost.

>Understanding the key dimensions and most the critical tolerances of the part is extremely valuable to both parties when developing the final part print. Is raw material cost a main concern, or is tooling cost their biggest issue? Getting this information up front is essential to develop a prototype or series of prototypes to meet their needs. With a brand new product, enough detail is needed to work out the best material to make a prototype that can be manufactured in a production scenario. The key is to use the prototyping process to identify ways to reduce costs and make the part manufacturable at the production phase in as short a time frame as possible.

>Prototypes vary tremendously depending upon the project, and a company may be called upon to produce everything from a one-piece prototype up to 10,000 pieces, for those parts where repeatability is a must. Prototyping should be used to initiate a dialogue on how to steer the project in ways that assure manufacturing consistency and reduce cost. Engineers may call out areas where they have concerns, point out exceptions, or look at dimensions and features that can be made without exorbitant tooling or added secondary operations. In those instances where the designed part does not meet a particular need, engineers would use the prototyping process to request a material change or redesign the part to increase its strength. Or, if a material is called for that is not available without making an inordinately high material purchase, engineers may suggest a material change.

>Soft tooling is utilised for most prototype orders. Soft tooling refers to simple form tools and standard items likely to be found in a tool maker's tool box drawer. Mounted in small die sets, the soft tooling can be used to produce prototypes in smaller numbers, before making the more sizeable investment in production tooling. This is frequently the best method for getting to the production phase. In some instances, a customer may commission low volume production tooling to help develop the prototype. If a significant number of parts is needed to bridge the lead time of full production tooling, bridge tooling may be used to produce parts for a short run. Bridge tooling refers to using low cost but accurate tooling to make low volume production.

>One example is a large medical device company, for whom CSS produces a stamped flat spring located underneath the water tank of a continuous positive airway pressure (CPAP) system used to treat sleep apnea. Working with the company, CSS developed an initial prototype, and worked through several design iterations before settling on a good design that could meet the requirements. A short run of 2500 proved the design, and more than 750,000 of the machines have since been manufactured.