Ejector Punches for Heavy Load with Dowel Holes - RP Coating

These heavy-load ejector punches are used in injection mold tooling where repeated ejection cycles demand stable alignment and high wear resistance. The dowel-hole design supports center locating/dowel hole setups, improving guiding accuracy for cores and moving components under load.

In automotive connector and sensor housing molds, ejector punches experience intermittent side loads during part release. The Al-Cr based RP coating with alpha treatment helps resist edge wear and coating breakdown at elevated contact temperatures, supporting longer punch life and reduced downtime.

For appliance and consumer electronics housings with thick-gate runners or tough polymer blends, punching forces and friction can accelerate wear on uncoated tools. This variant’s high hardness and improved coating adhesion are suited to maintain consistent ejection performance over extended production runs.

• Use with dies featuring dowel-hole centering for stable alignment
• Suitable where conventional coatings fail from thermal stress and edge wear

This punch family is offered in two cutting-tool type steel options suitable for high hardness applications. SKH51 equivalent (AISI M2 class) is a high-speed steel grade chosen for balanced wear resistance and toughness in repetitive punching and ejection.

Alternatively, SKH40 equivalent (powdered high-speed steel) provides a powdered-route steel structure for consistent properties in wear-critical tooling. In both cases, the key requirement is maintaining hardness at the contact surface during cyclic loading.

• Heat treatment state: Hi-speed steel punches are typically used after hardening and tempering to achieve working hardness; the exact resulting HRC can vary by supplier heat cycle.
• Wear resistance vs. toughness trade-off: higher hardness improves scuffing/edge-wear resistance but can reduce toughness under severe shock loading—tool geometry and fit should be selected accordingly.

The RP coating plus alpha treatment is intended to improve coating adhesion and reduce wear progression at the punch edge under high friction and heat.

Select the ejector punch size by matching the required shank diameter (D), tip geometry, and overall stroke envelope to your mold core/cavity arrangement. The shank diameter range is 10–45 mm, so choose D to fit the guide and prevent excess clearance that can cause side loading.

Choose tip shape (Round, Rectangle, Oblong, Double flatted round, or Radius rectangle) and then verify the tip dimensions: P = 2.5–35 mm, W = 2.5–9 mm, and tip corner R is specified as 0.15 mm (where applicable). Tip length is provided as B = L or S (based on your selected variant).

Confirm the overall length: L has ranges 60–150 mm, 70–150 mm, or 50–150 mm depending on configuration, and the full length alteration (LC) is 37–149.9 mm or 42–149.9 mm. Tip dimension alteration (PC) is 1.25–17.5 mm.

• Match the punch length (L/LC) to the required ejection travel and safe clearance
• Consider tolerance/fit in the guide bore to minimize wobble that increases edge wear
• Tip dimension alteration (PC/WC) enables fine tuning without changing the core guide size