This Small Business Innovation Research (SBIR) Phase I project aims to develop an effectively-thick coating (ETC) technology for machine tool applications. This technology will provide an effective thickness that is 5-20 times thicker than that of traditional coating while abating delamination issues that currently limit thickness. The approach is to micromachine the cutting tool to form a specific pattern followed by the deposition of coating via chemical vapor deposition (CVD) or physical vapor deposition (PVD) techniques.
The broader/commercial impact of this project will be the potential to obtain much thicker coating for machine tool, thus extend its lifetime and reduce costs. One of the challenges in the application of machine tool coating is that thin coating is usually worn away before the other parts of the machine tool are compromised, resulting in high cost. On the other hand, the coating tends to delaminate from the substrate when the thickness is over a critical point, making it very difficult to deposit coating with desired thickness. This technology will offer a coating with much higher effective thickness and is expected to extend the machine tool life time by a factor of 2.
Effectively Thick Coating (ETC) is a technology created and being developed by Endres Machining Innovations, LLC (EMI) of Houghton, MI, currently targeting Chemical Vapor Deposition (CVD) coated cutting tools for extreme abrasive wear applications. The ETC technology allows for standard 10-25 µm thick CVD coatings to be applied with an effective thickness of 60-200 µm thick in key locations without inducing prohibitive internal stresses that are inherent with 30+ µm thick coatings. This patented (US Pat. 7,651,758) technology is possible laser micromachining a pattern of micro-hairs into the base material (substrate) whereby the CVD coating is allowed to bond and grow from the sides of the micro-hairs in simultaneous fashion with the rest of the insert. With the effectively thicker coating, the benefits of wear resistance are extended by 5 to 10 times that of a standard coated tool with the same nominal coating thickness. EMI is primarily a R&D company specializing in advanced cutting tools for machining applications, CVD coatings and lasers are not part of EMI’s core competencies. The application of ETC was focused to a turning/facing operation using standard CPG422-Z22 inserts secured from Ultra-MET (Urbana OH). KMLabs (Boulder, CO) who specialize in ultrafast femtosecond (10-15 second) laser physics and laser construction was selected for the laser micromachining. KMLabs’ assistance with this project proved essential in producing prototypes that (a) could produce the micro-hair patterns in a reasonable amount of time (cycle time) and (b) that were still suitable for CVD diamond coating. CVD diamond coating services were supplied by sp3 Diamond Technologies (Santa Clara, CA) for standard diamond coating applications 10-28 µm thick. Engineering, testing, data analysis and logistical work was facilitated by EMI. Testing of the ETC technology was performed by measuring insert wear by cutting 10 inch A359-SiC 30% F400 metal matrix composite (MMC) discs, an exceptionally abrasive to machine material, in a facing operation at various cutting speeds. Data collected from ETC prepared inserts were compared against direct baseline tests (using a non-ETC prepared corner of the same insert) as well as polycrystalline diamond (PCD) tool baseline tests. Testing the ETC prepped prototypes demonstrated the ability for the micro-hairs to anchor the coating to the substrate and eliminate (or greatly retard, depending on the pattern tested) delamination induced chipping, allowing for improved tool life over traditional coated inserts at increased testing speeds at 800 SFPM [243 m/min] of and slower wear compared to PCD tooling. The outcome of the efforts put forth in Phase-1 has provided the justification for continued development of the ETC technology in a Phase-II, and ultimately Phase-IIB to bring this technology to market. Partnerships with KMLabs and sp3 Diamond Technologies have been established for Phase-II work and beyond as well as direct interest in the technology from leading companies in the cutting tool industry such as Kennametal and Seco. Interest from an end-user vantage has also been established for field testing trials when the technology is ready for MMC and carbon fiber reinforced polymers (CFRPs).
