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Novel DLC Coating
Published in Peerawatt Nunthavarawong, Sanjay Mavinkere Rangappa, Suchart Siengchin, Kuniaki Dohda, Diamond-Like Carbon Coatings, 2023
A progressive stamping is widely utilized for metal forming to produce the metallic parts from its work sheets. In the sheet forming of stainless steel parts, the punch and die inevitably suffer from severe damage without a protective coating. Among various steps in the progressive stamping of AISI304 sheets, the ironing and bending steps are taken as an example to demonstrate that nano-laminated DLC film works to significantly protect the tool steel punch from wear. As shown in Figure 1.16a, a plate is bent and ironed to fix an angled part. Since the punch edge is subjected to high-stress transients in these continuous steps, the DLC coating is necessary to protect it from severe damage. When using the mono-layered DLC film, several surface areas of film are scratched away and delaminated to leave an original tool substrate surface. Figure 1.16b compares the mono-layered DLC films before and after bending and ironing steps in a single shot. A partial delamination occurs elsewhere on the contact interface to AISI304 stainless steel sheet. Let us exchange this mono-layered DLC film with the present nano-laminated DLC one in preparation of the punch. Figure 1.17 shows the variation of the nano-laminated DLC film surface with increasing the number (N) of bending and ironing steps in the same progressive stamping. No significant change is detected on the nano-laminated DLC film surface condition even at N = 2000. This proves that high hardness and toughness of nanolaminated DLC film provides a way to certificate the long tool life even in the dry stamping conditions.
Manufacturing methods for metallic bipolar plates for polymer electrolyte membrane fuel cell
Published in Materials and Manufacturing Processes, 2019
Oluwaseun Ayotunde Alo, Iyiola Olatunji Otunniyi, HCvZ Pienaar
A line of stamping dies typical of conventional stamping process can potentially produce 10 to 14 parts per minute,[199] which translates into a minimum of 4.29 sec/part. This rate is far lower than what will be required to meet the 500,000 systems per year target. A form of the stamping process, known as progressive stamping, which uses a progressive die, has been identified as a more promising option to meet the high volume production requirement of the PEMFC BPs.[11] This process enables the metal sheet to be fed directly from the coil into the tool, thereby eliminating the need and costs of blanking and transferring of blanks to the die. Other advantages of the progressive stamping over conventional stamping include higher production speed, quick setup, less scrap material, longer runs, high repeatability and lower cost per part.[199]