Rubber Compression Moulding Process Parameters

In this post, we will discuss what factors needs to consider while setting process parameters – Temperature, Time & Bumping for Rubber Compression Moulding Process

What are the factors to consider while setting this parameters

1. Temperature

Compound TS2 Induction Time Value in ODR Rheometer

TS2 Induction Time. After this, the rubber will starts its curing process and becomes hard and resist to flow.

TS2 Value	Temperature Preferred
< 0.50 min	160 Deg
0.50 – 0.80 min	165 Deg
0.80 – 1.00 min	170 Deg
1.00 – 1.5 min	175 Deg
> 2 min	> 180 Deg

Product Thickness

If Product Thickness more, slow curing / Less Temperature preferred (for good flow of rubber into the cavity)

If Product Thickness Less, More Temperature Preferred

Preform Width / Thickness & Placement

Preform Width, Thickness & Placement are the three parameters that help the rubber to quickly flow into the cavity

If the flow is quick, then more temperature preferred

If the flow is not quick, then slow curing preferred (Otherwise rubber will become scorch)

Time Required to load Pre forms in Moulds

If more time required to load pre forms in moulds, then slow curing / less temperature preferred (Otherwise rubber will become scorch)

If Less time required to loads pre forms in moulds, then more temperature preferred

2. Curing Time

TC90

TC90 (90% Curing Completion). Based on this & Set temperature, curing time to be decided

3. Bumping

Bumping will help rubber to quickly flow into the cavity and eliminates air problem defects

Bumping required for following situations,

1. If TS2 induction time is Less than 0.8 min (Eg – Nitrile, EPDM) – (Rubber Needs to flow into the cavity before its scorch state, So Bumping will help to flow rubber quickly into cavity)

2. If Pre form width, Thickness & Placement incorrect – Bumping required to flow rubber quickly into the cavity

3. If Product Shape Complex