US Synthetic Bearings Site

Geometry

Reduction angle and bearing length are determined by materials and area of reduction. More

Carbide vs PCD vs SCD

Wire drawing dies are made of several materials including tungsten carbide, natural diamond, synthetic single crystal diamond, and polycrystalline diamond (PCD). Selection of a die often depends on the material being drawn and the desired surface finish of the wire.

Tungsten Carbide

Tungsten carbide is a good solution in a number of circumstances:

When drawing large diameter wire, tungsten carbide requires less investment than the alternatives
When evaluating the effects of various die geometries
Where consistent diameter and ovality are not critical

Polycrystalline Diamond

PCD is a matrix of diamond grains that are grown together using proprietary diamond presses. The interlocking grains provide extremely high abrasion resistance. Characteristics of PCD include:

Superior toughness over single-crystal diamond due to randomly oriented grains
More uniform wear than a single-crystal diamond
High thermal conductivity and hardness
Extended wear relative to tungsten carbide

	PCD Materials Properties
DENSITY	3.90 g/cm³	Bertagnolli, US Synthetic
COMPREHENSIVE STRENGTH	6.9-7.6 GPa	Roberts, Debeers
TENSILE STRENGTH	1.3-1.6 GPa	Cooley, US Synthetic
YOUNG'S MODULUS	841 GPa	Roberts, Debeers
FRACTURE TOUGHNESS	13-15 MPa√m	Jiang Qian, US Synthetic
HARDNESS (Knoop)	49.8 GPa	Debeers
COEFFICIENT of LINEAR EXPANSION	1.3-3.9, 10^-6/°C	Glowka, SNL
COEFFICIENT of FRICTION	0.05-0.08	Sexton, US Synthetic
THERMAL CONDUCTIVITY	543 w/m-K	Lin, UC Berkeley

Single Crystal Diamond

Single crystal diamond result in a superb surface finish on wire. Available both as natural diamond and synthetically grown diamond. Prices for large single crystal stones makes dies above .025 inches (0.63 mm) increasingly expensive. Good applications for single crystal dies are in very small diameters and high surface finish requirements.