SUMMER 2018

174 THE DISTRIBUTOR’S

174 THE DISTRIBUTOR’S LINK SPIROL COLD HEADED VS MACHINED SOLID PINS from page 144 The purpose of a chamfer is to allow for ease of assembly. A chamfer angle between 25° – 40° is suitable for the vast majority of Solid Pin applications and allows for maximum pin engagement. From a manufacturing standpoint, the optimal cutting angle (machining) is 45°, while the optimal forming angle (cold heading) is 30° or less. EXAMPLES OF COMMON MATERIALS Material Cold Heading Machining Austenitic (nickel) stainless steel Martensitic (chrome) stainless steel Low carbon steel Alloy steel Aluminum Excellent corrosion resistance Corrosion resistant High shear strength High hardness Versatile Low cost High shear strength High hardness Corrosion resistant Lightweight Lead free 305, 302 HQ 303 410 420 1022 12L14 6150, 4037 4150 5056 2024, 6061 TABLE 3 NOTE: THIS LIST CONTAINS SOME OF THE COMMON AVAILABLE MATERIALS (OTHERS ARE AVAILABLE) Material The most common materials for Solid Pins are carbon and stainless steels. Raw materials are available in different forms depending on whether pins will be machined (rod) or cold headed (wire). Commercially available material grades for rod and wire can differ. Rod is available in material grades best suited for machining, while wire is available in material grades suited for cold heading. Although material grades may differ, the important take away is that there are equivalent materials available for headed and machined Solid Pins. Hence, best engineering practices dictate that material specifications on drawings be relatively general if possible (i.e. carbon steel with hardness rating RC 27-33). Table 3 shows examples of several common materials for cold heading and machining for reference. Cost Comparison - Cold Headed vs Machining Machined Solid Pins are typically about ten times the cost of cold headed Solid Pins. Why are cold headed Solid Pins so much more cost effective? COST OF RAW MATERIAL ($/LB) ¤ Cold heading produces Solid Pins at a rate of about 300 parts per minute (ppm), while machining yields approximately 4 ppm. ¤ Machining generates scrap. Hence, more raw material is needed to machine a Solid Pin than to cold head the same part. The only scrap generated during cold heading is that which is produced during set up. ¤ Ground OD rod can cost more than three times as much as standard rod used for machining. PIN DIAMETER TOLERANCE VS RAW MATERIAL COSTS Ground OD Rod (Machining) Standard Rod (Machining) 0 0.0002 0.0004 0.0006 0.0008 0.001 0.0012 0.0014 0.0016 0.0018 0.002 TOTAL PIN DIAMETER TOLERANCE (INCHES) GRAPH 1 Wire (Cold Heading) CONTINUED ON PAGE 184

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