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RECOMMENDED HEAT TREAT CYCLES PRIOR TO TD TREATMENTD-2 There are two options when hardening D-2 before coating, for the best stability and size control we recommend Double High Temper heat treat. Temper the steel at 975°F two (2) times for two hours. If Post Hardening of D-2 is required (for compressive strength), temper at 350°F / 400°F two (2) times for two (2) hours per temper. Examples
A-2
M-2
H-13
CPM-10V
When machining large sections where extensive stock removal is necessary, parts should be stress relieved prior to semi-finish machining. Rough machine, heat to a temperature of 1200-1250°F. Hold for two (2) hours, cool slowly (anneal), then semi-finish machine. Plan to finish dowel holes after coating. A typical cycle for a piece of tool steel should be as follows:
POST HARDENING OF TOOL STEELS AFTER TD TREATMENT FOR IMPROVED COMPRESSIVE FORCETD treatment results in a slightly under-hardened substrate in most air-hardening tool steels (see-Guidelines For Tool Steel Selection). The result is increased substrate toughness, which in some cases is highly desirable. However, in applications where substrate hardness is critical, post-hardening is recommended to increase the substrate hardness of TD-treated tool steels. This provides a stronger support for the Vanadium Carbide layer (TD treatment) which improves performance and extends tool life. Post-hardening is especially recommended when high forming pressures are encountered. Examples include forming or drawing of heavy gauge, high strength/low alloy steel, and all types of heavy gauge stainless steel, roll forming of high strength/low allow steel and most grades of stainless steels. The hardness of AISI-D2 or Vanadis-4 (powder particle steel) can be increased to Rockwell “C” 59/61 by post-hardening. High speed steels such as AISI-M2, M4 or other powder particle steels such as CPM-10V, CPM-15V, CPM-M4 and Vanadis-10 can all be raised in hardness to above Rockwell “C” 60 by the post-hardening service. When post-hardening is recommended by the Columbus Components Group TD Center, it is quoted as a separate operation. It requires one to two additional working days over normal TD processing time. REDUCED LUBRICANT USAGE ON TD-TREATED TOOLINGTD treatment produces an extremely hard surface layer that is diamond polished on all forming surfaces, resulting in a very low coefficient of friction. Consequently, the reduction of lubricant with TD-treated tooling can be significant; in some cases, lubrication can be eliminated. The exceptions where lubricants will be necessary are when forming soft materials (aluminum) or coated materials with soft and “gummy” types of surface treatments, such as aluminized steels, zincro metal, galvanized steel, galva-lume, etc. With these materials, forming pressures that generate high temperatures will cause excessive flaking or galling if lubricants are not used. TD treatment in these applications will significantly enhance tool life and reduce pick-up and galling. In several documented cases, petroleum-based lubricants have been replaced by water-based types, resulting in significant cost savings. In general, lubricants used in the metal forming industry will not affect the TD-treated surface. The Vanadium Carbide layer (TD treatment) is highly impervious to any type of oxidation from substances as aggressive as acid-type solutions. For safety, we recommend that when changing to lubricants of unknown composition, testing be performed on a TD surface. Reduction of lubricant on TD-treated tooling should be performed gradually. In most cases, the amount of lubricant reduction is dictated by the amount of heat generated during the operation of the tooling. Tool life comparisons at different lubrication levels should be studied for the best economies. GUIDELINES FOR SELECTING TOOL STEEL GRADES WHEN CONSIDERING TD TREATMENT
POLISHING OF TOOLING PRIOR TO TD-TREATMENTThe Vanadium Carbide Layer produced by the TD Process is extremely hard. It is therefore very important that the surface finish of the tooling be smooth and free of all tool marks. Key points to be considered are surface roughness and polishing direction. In all cases the surface finish should be 5 to 8 RMS micro-inch (0.125 to 0.2 micro-meter) or better on the working surface of the tooling. When working with coated/plated steels, stainless steels, high strength steels or abrasive type materials the surface finish of the tooling should be 1 to 5 RMS micro-inch (0.025 to 0.125 micro-meter) or a “mirror” finish. The polishing should be performed after finish grinding of the wear areas. Buffing, starting with emery paper or stone #200 grit and the progressively finer grit to #1000 is recommended. The Tool can be finish buffed with 3-7 micron diamond compound. All tool and grind marks must be removed. In forms or draws where a radius transitions to a wipe area, make sure this area is blended and smoothed to a true radius with no sharp transition. It is recommended that the polishing direction be the same as the metal flow (see sketches below).
Maintenance of coating during use. If galling or pickup occurs on TD treated tooling, try the following:
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