Hexagonal puches are used in the fastener manufacture and metal working industries for their precision and durability. However, hexagonal punches during production often suffer from corner breaking, cracks or other damages, which not only affects product quality but also increases production costs. This article will explore the primary reasons for hexagonal punch corner breakage and review effective prevention measures for manufacturers to improve mold lifespan and reduce wear.

Primary Reasons for Breakage of Hexagonal Punch Corners

1.1. Improper Material Selection

If the material was hardened poorly or inconsistently, the force of high-pressure impact can cause those materials to fracture.

Material Toughness must be high to withstand extended impact loads.

1.2. Problems with Heat Treatment Process

This leads to the punch being brittle and susceptible to corner breakage if it was quenched at a temperature too high or was not tempered properly.

Residual Stress: Improper tempering will create residual stress in the punch, which may lead to cracks when in use.

1.3. Lack of Machining Accuracy

Excessively out of spec hexagonal dimensions may lead to a mismatch of the punch with the die, leading to uneven distribute of the process stress on the punch, and, more importantly, possible failure mode governed by corner breakages.

Over Grinding Heat: Heat is generated when grinding to overcome the forces that act on the pair, resulting in small hairline cracks on the surface, which reduces life.

1.4. Incorrect Stamping Parameters

Excess Pressure: To exert too much pressure will exceed the breaking point of the punch and break the punch.

High Speed: In stamping, at a high stamping rate, the punch might not happen to cool down; thus thermal fatigue damage takes place.

1.5. Harsh Working Environment

Long exposure to heat or humidity can also contribute to aging, and weaken the punch.

If the dies are in a dirty environment, metal debris or contaminants can enter the die and apply excessive load onto the punch edge, leading to damaged edges.

So how do we prevent hexagonal punch corner breakage?

2.1. Choose High-Quality Materials

Choose high-speed steel (SKH-9, SKH-51, SKH-55), powder steel (ASP23, ASP30), or tungsten carbide (YG15, YG20) as the material to ensure a balance between wear resistance and toughness.

✅ Use materials with consistent hardness to reduce internal stress and improve impact resistance.

2.2. Hotop Working Modernization Process

✅ Do not quench to high a temperature to prevent the punch from being completely hardened and yet be tough enough.

✅ Proper tempering: Proper tempering removes residual stress and improves the punch’s mechanical properties. Durability is improved with secondary tempering.

✅ Cryogenic Treatment: Cryogenic treatment of the punch to -196°C increases hardness and reduce the amounts of micro-cracks.

2.3. Improve Machining Precision

✅ Shapes Hexagonal Punches by high-precision CNC machining to make sure they can fit into the die correctly.