Tungsten Carbide Powder for Wear Parts & Dies

This table spans the entire range of wear part applications—notice how dramatically different they are from each other. Wire drawing dies face pure abrasion and use very low cobalt (3-6%) for maximum hardness. Cold heading dies face repeated violent impacts and use high cobalt (12-16%) or even higher for toughness; some cold heading applications use up to 25% cobalt. The "Wear Type" column tells you the dominant mechanism, which drives the grade selection. The "Die Life" column gives you realistic expectations—wire drawing life is measured in millions of meters of wire; stamping in millions of strokes. Use this table to find your application and see what specifications you should be targeting.

A wire drawing die isn't just a hole—it has four distinct zones, each with a specific job. The entrance cone catches the wire and holds lubricant for smooth drawing. The approach cone does the actual size reduction—this is where most wear happens as the wire is compressed through the narrowing passage. The bearing zone sizes the wire precisely and burnishes the surface to final quality. The back relief lets the wire exit cleanly without scraping. Understanding these zones helps you diagnose wear problems: if the entrance wears prematurely, your wire is misaligned or you have lubricant issues; if the bearing wears, that's normal operation. Each zone can be optimized separately during die design.

The approach angle (also called the reduction angle or drawing cone) determines how aggressively you reduce the wire diameter. The angle is usually expressed as the included angle (2α), though some references use the half-angle (α). Soft metals like copper and aluminum can handle steeper angles (12-16°) because they flow easily under pressure and don't work-harden excessively. Hard metals like high-carbon steel and stainless steel need gentler angles (8-12°) to avoid work hardening, surface cracking, and excessive drawing force. The rule is straightforward: harder material = narrower angle; larger area reduction per pass = wider angle. Getting this wrong causes excessive die wear, surface defects on the wire, or even wire breakage during drawing.

Bearing length is the parallel section that determines the final wire diameter and surface quality. It's expressed as a percentage of the wire diameter. Finer wire needs proportionally shorter bearing because there's less contact area and friction heat builds up faster in a confined space—a bearing that's too long on fine wire causes overheating and potential wire breakage. Coarser wire can handle longer bearing, which gives better size control and longer die life because the wear is distributed over more surface area. Too short a bearing results in inconsistent sizing and poor surface finish. Too long causes excessive friction, heat buildup, and potential wire breakage. The percentages shown are starting points; fine-tune based on your specific wire material and drawing speed.

Different wire materials create different demands on the die grade. Soft metals like copper and aluminum tend to stick (adhesive wear), so you need smooth polished surfaces and sometimes coatings to prevent material transfer. Steel wires cause more abrasive wear, so you need harder grades. Stainless steel work-hardens during drawing, increasing the drawing force progressively and causing more wear—use slightly tougher grades with more cobalt to handle the increased stress. Refractory metals (tungsten, molybdenum) are extremely hard and will wear through soft dies quickly—use the hardest grades available (94+ HRA). Fine copper wire is a special case requiring ultra-fine grain (0.5-0.6 μm) because the die bore is so small that even minor wear causes significant dimensional variation.

Progressive stamping dies have multiple components, each with different requirements—don't use the same grade for everything. Punches take the brunt of impact when blanking (cutting through the sheet metal), so they need higher cobalt for toughness. The die (female part) experiences more sliding wear as the blank is pushed through, so it prioritizes wear resistance with slightly lower cobalt. Strippers face repeated fatigue loading as they push the strip off the punch millions of times—they need high TRS. Pilots require precision first (to locate the strip accurately) and wear resistance second. Optimizing each component separately can significantly extend overall tool life compared to using one grade for the entire die set.

The material you're stamping determines how your dies will fail, so adjust your grade selection accordingly. Stainless steel work-hardens and sticks aggressively to uncoated carbide—you'll likely need TiN or TiAlN coatings. Aluminum is notorious for galling (severe material transfer)—coatings are essential, not optional; uncoated carbide dies stamping aluminum will fail quickly from buildup. High-strength steel (AHSS, UHSS) hits harder and abrades more aggressively than mild steel—you need both toughness (more cobalt, coarser grain) and possibly coating for the combined challenge. Copper and brass smear rather than gall, so polished surfaces help more than coatings. Always adjust your grade to the specific workpiece material, not just the operation type.

Cold heading is brutal on tooling—each stroke is essentially a controlled explosion of force that compresses a metal blank into a fastener head or complex shape. The header die (first blow die) takes the worst abuse and uses the highest cobalt content (14-18% or even higher—some applications use up to 25% cobalt). Punches need slightly less toughness but still face severe impact. Point dies and extrusion inserts have more controlled loading but still require high TRS. The "Life Expectancy" column sets realistic expectations: even the best grades only last 0.1-2M parts depending on the component and fastener material. Don't expect cutting tool life from cold heading dies—the loading is fundamentally different.

Harder materials hit harder—this is the fundamental reality of cold heading. Low carbon steel is the baseline that standard grades can handle. As you move to medium carbon, alloy steel, and especially stainless steel, you need progressively more cobalt and coarser grain to survive the increased impact forces. Stainless steel is particularly challenging because it work-hardens during heading, meaning each subsequent blow is harder than the last as the material becomes stiffer. Grades with 18-25% cobalt are common for stainless heading. Non-ferrous metals (aluminum, copper) are easier on the carbide in terms of impact, but watch for galling—material transfer that builds up and ruins dimensional accuracy.

Hot extrusion presents a unique challenge: the die softens significantly at operating temperature. A grade that measures 91 HRA at room temperature might only be 78-80 HRA at 800°C—a dramatic drop in wear resistance. Higher temperatures require more cobalt to handle thermal shock (the temperature swings as each billet enters and exits), but more cobalt also means more softening at temperature. Above 800°C, consider adding TiC (titanium carbide) to the formulation—TiC maintains hardness at elevated temperatures better than pure WC-Co. The room temperature HRA values shown are just the starting point; what matters is the hot hardness at your actual operating temperature.

This diagnostic table helps you identify what went wrong when a die fails. Uniform wear is normal and expected—plan your regrind schedule around it. Galling (material transfer/scoring) is an adhesion problem indicating workpiece material is bonding to and tearing from the die surface—the solution is usually a coating (TiN, TiAlN, DLC), not a grade change. Chipping means the grade is too brittle for the loading—add cobalt. Cracking patterns tell you whether the problem is thermal (radial cracks from center) or fatigue (circumferential cracks)—both benefit from tougher grades. Spalling (surface layers peeling off) indicates subsurface fatigue crack propagation—demand cleaner material with lower porosity. Look at your failed die, match the symptom, and apply the prevention strategy for your next die.

Premium die grades have tighter specifications than standard grades—and the premium is justified for high-volume production where die failure is expensive. Porosity is especially critical: pores are stress concentrators where fatigue cracks initiate, and dies under cyclic loading are essentially doing fatigue testing on every pore in the material. Demand A00-A02 porosity rating (ISO 4505) for dies that will see millions of cycles. Hardness and grain size uniformity ensure consistent wear across the entire die face—if one area wears faster, your products go out of tolerance prematurely. TRS variation matters for predictable maintenance scheduling: you can't plan die changes effectively if some dies fail at 500K cycles and others at 2M cycles.

This table reveals the economics of premium grades. The key insight is that cost increase often lags behind life increase: a grade that costs 30% more but lasts 50% longer is a good investment. Nano-grain grades cost 3-4× more but can last 3-5× longer—worth it for high-volume production where downtime for die changes is expensive. For prototyping or low-volume work, standard grades are fine because die life doesn't significantly affect total cost. Match your investment to your production volume: calculate the total cost per part including die cost, regrind cost, and downtime, then see which grade minimizes that total.