Consider device fit, form, and function as well as materials, volume, cost, and more.
In the March 29th online issue of MDDI Qmed, MICRO Executive Vice President Steve Santoro wrote about choosing metal stamping or machining for metal-based medical devices. The article compares the two processes and discusses the considerations that must be taken into account by the designer —and how they relate to disposable and reusable instruments.
You’re developing a metal medical device and balancing a budget, deadlines, design considerations, and more. Which process do you choose—stamping or machining? MD+DI asked metal manufacturing veteran Steve Santoro, executive vice president for MICRO, to compare the two processes as well as look forward to the future in metal manufacturing. Santoro has been at MICRO since 2002 and has been in the contract manufacturing industry his entire career.
MD+DI: What are the basic differences between stamping and machining when it comes to medical devices?
Santoro: The main determinant when considering stamping versus machining has to do with the fit, form, and function of a component coupled with the geometry of the part and material used. If a medical device is designed for an indefinite number of uses, then machining works best, as it produces complex parts that support durability. For products that are meant to be used just one time, stamping is a better approach as it can produce precision parts that tend to be less durable.
Volume can also be a significant driver in the decision-making process. When several million components a week are needed, such as ligation clips, this can be easily achieved with stamping. To machine such quantities might require 100 machining centers. Thus, scaling to this degree with machining may not be practical in terms of capital outlay.
Tooling costs are another consideration. For example, if a device requires tight tolerances of +/-0.0005 inch and has volumes of 3000-5000 pieces a week, machining usually is the technology of choice as it is more versatile and precise. Assuming the right machining center is available, it merely needs to be programmed to accommodate the part geometry. This is in sharp contrast to a progressive stamping die, which will take longer to design and build, in addition to being costlier.
Part geometry is also a major consideration. There are some components that simply cannot be stamped. For example, a part made of full hard 304 stainless steel, 1/8-in.-thick with a hole that is 0.040 diameter cannot be stamped. There is no punch material that can take the load required to pierce that material at that diameter. Machining works best in this case coupled with laser technology.