![]() The result is a very hard, wear-resistant surface with good release properties. Dislocations further into the bulk metal are 'pinned'. Have you considered coating with diamond-like carbon (PECVD), then ion-implant using a few hundred KeV nitrogen ions? One ends up with a nitride/carbide layer within the surface which is in compression, not tensile, so is not dependent on the young's modulus of the substrate. Have you tried electrospark sputter deposition of these coatings? Some of our clients with screw machine collets, where galling is common, have benefited by this process. The suggestion of using a Titanium diboride or Chromium carbide coating appears to be a sound one. However, a coating added to the pins before the cryogenics will work synergistically with the cryogenics. We have achieved excellent results for our customers by just doing this. This will convert the retained austenite to martensite, stabilize the mold metal, and will increase the wear resistance of the moving parts of the mold and the gates and runners. Since there is very little clearance in ko pins, the part seizes.Ĭryogenically treat the mold and pins. The martensitic crystal is larger than the austenitic crystal and the part grows as the austenite is transformed by the heat and vibration of molding. All heat treaters leave between 9% to 20% retained austenite. Are you sure a coating is necessary? Our research shows that a lot of the galling created in mold knock out pins is created when the retained austenite in the pins transforms to martensite. If this is for a die casting operation and the pin surface is in contact with the molten aluminum at some point then I would definitely suggest using Titanium boride if you can find a supplier but otherwise use CrC.Ī. Most all of these are available through the larger coating houses. Other coatings that might work better for you include TiAlN, AlTiN, Aluminum oxide. ![]() As far as hard coatings go TiN is really the bottom of the barrel. Titanium Nitride has taken over some of the applications formerly associated with hard chrome plating and has proven better sometimes, but not always! Have you tried chrome plating - which offers not only hardness and wear resistance, but lubricity and low coefficient of friction as well?Ī.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |