Many facilities rely on parts punched or stamped from flexible/semi-flexible materials to satisfy OEM production or MRO activities. Traditionally referred to as “die cut parts”, these include parts produced from elastomers and other materials, including gaskets and seals, replacement or refurbishment parts for machinery and equipment, and custom fabricated parts designed to improve the performance or extend the life of process equipment and machines.
The term “die cut” originated when the common method of producing parts from rubber or other flexible materials was to place material over a die and use a press to apply vertical pressure on the material against the die, resulting in a cut (or “stamped”) part. This method of production, while still used, has given way to CNC methods of production where computer-controlled technology is used to cut the finished part. Today, the term “die cut” is often used generally to describe the production of parts where the use of dies may or may not be required.
In many cases, the costs for procuring die cut parts can represents a significant part of an organization’s MRO budget. An important contributor to these costs are the charges for the tooling required to produce the parts: the dies needed to cut or stamp the final part. In this article, we present several tips for reducing the tooling costs associated with die cut parts, resulting in lower part costs and bottom-line savings.
Computer-controlled (CNC) production methods are now available that eliminate the tooling needed to produce die cut parts. For example, elastomeric gaskets and seals can now be easily produced by CNC waterjet or flex/flash cutting, eliminating the need for stamping dies. This eliminates the tooling costs entirely, resulting in lower part costs.
CNC technology can be used to produce a wide variety of parts that were previously produced by die cutting or stamping, or even molding. This includes parts made from elastomers, foams and sponges, plastics, composites, non-wovens, and more. Examples of parts that can be made on CNC technology without the use of cutting or stamping dies include:
As well as producing parts from flexible materials, CNC production methods can also be applied to produce parts from plastics or other rigid materials. With specialized CNC equipment it is now possible to machine and mill plastic parts in low, moderate and high volumes. CNC machining of plastics is a viable alternative to molding, especially where highly customized are required.
Parts traditionally made by die cutting can be produced by alternative production methods, including CNC production (described above) and molding. A key question is, when does it make economic sense to produce a part by die cutting, CNC cutting, or molding? The answer is that it depends on a number of factors, including the following:
As with many business decisions, choosing the right production process for a given part requires considering the tradeoffs involved with each of the factors listed above.
Die cutting works well for low to moderate production volumes and where the part geometry is relatively simple. Tooling costs for die cutting are relatively low ($500 – $1500 is typical), compared to molding. Nonetheless, the tooling costs can represent a significant proportion of the final part cost when production quantities are low. In addition, depending on part complexity, die cutting has a relatively higher material scrap rate (low yield) and may require secondary operations to produce the finished part. All of these factors can conspire to drive up the cost of the finished part.
As noted above, CNC cutting (or machining) eliminates tooling costs. Because it is possible to nest parts to maximize material usage, yields with CNC cutting tend to be much higher than die cutting. The greater precision of CNC technology also results in higher part quality and finish than is possible with traditional die cutting. The low setup times of CNC equipment also makes this production method well-suited for low as well as high production quantities.
Rotary die cutting is an interesting process that offers a superior alternative to traditional die cutting for the production of parts in very high volumes. In rotary die cutting, an automated tool with many die cavities rotates at high speed and contacts the material to cut the part, resulting in a high production rate. Rotary die cutting also supports the high-volume production of parts that require kiss cutting or supplied on a pressure sensitive adhesive (PSA) backing.
Molding often involves much higher tooling costs than die cutting. However, with molding, it is often possible to add more cavities to the tooling, resulting in a faster production rate than with die cutting. Depending upon the mold quality, secondary operations to remove flashing may or may not be needed.
Breakeven analysis for die cutting versus molding often shows that the breakeven point for the two processes is often highly dependent upon material value as well as production volumes. This is especially true in cases where the scrap produced by molding can be recycled through the production process.
As a general rule, molding should be considered as a preferred process for parts where order volumes are very high, where the material is not amenable to CNC cutting or machining, and where it is possible to use tooling with multiple cavities which will enable shorter production times.
For over 30 years, CRG has supported our customers’ needs for OEM or MRO parts fabricated from a variety of materials. Our production methods range from traditional die cutting and hand fabrication to the latest CNC technology and molding, allowing us to serve our customers with the most cost-effective process. Through our global supply chain, we stock a wide array of materials, including elastomers, foams and sponges, non-wovens, and plastics. To find out more about how we can support your requirements, please contact our sales team at email@example.com.
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