Bolts for Plastic Mold

Name: Bolts for Plastic Mold — Hex Socket Head Cap Screws & Shoulder Bolts
Brand: Axiom Molds
Availability: InStock
Rating: 4.9 (128 reviews)

Precision hex socket head cap screws, flat head variants, shoulder bolts, and positioning screw plugs for reliable injection mold plate clamping and component retention. Grade 10.9 alloy steel with black oxide finish.

Bolts for Plastic Mold — 10+ Products

MSBL Precision Shoulder Bolts

Coarse precision shoulder design for plastic mold fastening. Configurable length.

CBHS Type Hex Socket Head Cap Screws — Small Head

CBHS Small Head Cap Screws

Small head profile for tight-clearance mold assemblies. Coarse thread, fast delivery.

CBA Type Hex Socket Head Cap Screws — Through Hole

CBA Through-Hole Cap Screws

Through-hole hex socket cap screws for secure mold plate clamping.

JIS Option Flat Head Hex Socket Cap Screws

JIS Flat Head Cap Screws — 10.9 Grade

Flat head hex socket cap screws with black oxide. Grade 10.9 steel for reliable clamping.

Screw Plugs for Core Pin — Fine Thread MSWPN

Core Pin Positioning Screw Plugs — MSWPN

Fine-thread screw plugs for secure core pin retention. MSWPN type.

Positioning Screw Plugs — Coarse/Fine

Positioning screw plugs with coarse or fine threads for stable mold alignment.

Bolt Head Style Selection

Head Style	Profile	Counterbore Depth	Best For
Standard Cap	Cylindrical head, standard height	Standard (per DIN 912)	General mold plate clamping — default choice
Small Head (CBHS)	Reduced diameter head	Shallow (saves plate material)	Tight-clearance assemblies where standard heads interfere
Flat Head	Conical head, flush with surface	Countersunk (cone-shaped)	Parting line bolts where head must not protrude

Selection rule: Use standard cap screws for all general clamping. Switch to small head when the bolt pattern conflicts with nearby features (cooling channels, guide pin bores). Use flat head only at the parting line where protrusion would prevent mold closure.

📖 In-Depth Technical Guide: Read our full analysis onHow to Choose Hex Socket Bolts for Plastic Molds →

Torque Specification Quick Reference

Recommended tightening torque for Grade 10.9 hex socket cap screws in mold assembly (dry, unlubricated):

Bolt Size	Torque (N·m)	Clamp Force (kN)	Common Use
M6	12.5	8.6	Small mold plates, insert retention
M8	29.5	15.1	Standard cavity/core plate clamping
M10	58	24.0	Medium mold bases
M12	100	34.0	Large mold bases
M16	245	63.0	Heavy-duty mold plate clamping
M20	480	99.0	Die-casting mold assembly

Note: Reduce torque by 20% when using lubricated bolts or anti-seize compound. For heated molds (>80°C), re-torque after the first thermal cycle to compensate for thermal relaxation.

Application Scenarios

Cavity/Core Plate Clamping

Pain point: Injection pressure (50-150 MPa) acts to separate mold plates. Insufficient bolt clamping force causes flash at the parting line.

Why it fits: Grade 10.9 cap screws provide high-strength clamping with controlled preload. Cross-pattern tightening ensures uniform plate contact.

Core Pin Retention

Pain point: Core pins must be secured against ejection force without rotating or backing out during the molding cycle.

Why it fits: MSWPN fine-thread positioning screw plugs provide secure retention with precise thread engagement, preventing core pin movement under cyclic loading.

Engineering Resources

Selection Guide

How to Choose Hex Socket Bolts for Plastic Molds

Head style selection, torque specs, and tightening sequence for mold assembly.

Technical Guide

Why Proper Fastener Torque Matters in Mold Assembly

Torque-tension relationship, thermal compensation, and failure prevention.

Frequently Asked Questions

What is the minimum bolt grade for injection mold assembly?+

Grade 10.9 (ISO 898-1) is the industry standard minimum for injection mold plate clamping. Grade 8.8 does not provide sufficient clamping force to resist typical injection pressures (50-150 MPa). Grade 12.9 is available for extreme applications but is more susceptible to hydrogen embrittlement.

Should I use thread locker on mold bolts?+

Generally not recommended for mold assembly bolts — molds require regular disassembly for maintenance. If bolts are backing out due to vibration, check for inadequate preload (torque too low), thermal cycling effects, or damaged threads. For permanent installations only, use medium-strength threadlocker (Loctite 243 or equivalent).

What is the difference between positioning screw plugs and standard screw plugs?+

Positioning screw plugs (MSWPN) are designed to hold components in position (core pins, inserts) and have fine threads for precise adjustment. Standard screw plugs (MSWZ) are designed to seal fluid passages (cooling channels) and prioritize sealing over positional accuracy.

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