Injection Molding
About Injection Molding
Injection molding rubber is a combination of injection and transfer molding that Coi Rubber Products uses quite frequently to maximize the number of cavities in a given footprint. It is commonly used within liquid injection and/or LSR molding. Some classifications with liquid injection versus transfer injection would further provide subcategory classifications.
Injection Molding
- Perfect for large volume runs of small-to-medium size parts
- Good for intricate metal inserts, thin-wall diaphragms and similar components requiring uniform physical properties
- 300 ton to 1000 ton clamping pressure
Advantages of Injection (LSR) Molding Rubber:
- Tooling can be more complex and higher precision than compression
- Material properties created within A/B mix can have superior properties
- Process is suitable from most elastomers and cure systems
- Cycle times may be shorter reducing time while increasing efficiency
- Complete elimination of pre-forms, a labor-intensive step that can introduce variability in pre-form weight and shape resulting in variability of the finished product.
Disadvantages of Injection Molding vs. other rubber molding methods
- Labor for preforming material can add cost (however offshore manufacturing curtails this problem)
- Cycle times may be longer (additional shifts counter this problem)
- Tooling can be more complex and higher cost to construct than compression
- Higher percentage material runner scrape vs. compression molding
Have a question? Please fill out the form below to receive information regarding your inquiry. You may also give us a call at (626) 965-9966.
When rubber injection molding is the right process
Choose injection over compression when you need volume, consistency and fewer manual steps. Preforms are eliminated, the part cures in a closed mold, and flash is lower.
Good fits: diaphragms, bellows, seals with metal inserts, small precision parts, and parts that must match from the first shot to the last.
The trade-off is tooling. Injection tooling costs more than compression tooling, so it pays back at higher volumes. For low volumes or large parts, compression or transfer molding may cost less. See Compression Molding and Transfer Molding to compare. What helps us review a part: drawing, material and durometer, yearly volume, insert details, and the dimensions that matter most. Send a drawing or sample through the quote form and we will review it with you.