Definition
Clamp close is the stage of the Molding Cycle where the Clamp advances the moving platen to bring the mold halves together and lock them up before injection. It is the first motion of every cycle.
The three speed phases
- Fast approach: the platen moves quickly across most of the stroke to save Cycle Time.
- Slow / mold protection: near touch it slows to a low-pressure creep so the controller can detect an obstruction — a stuck part or misplaced insert — before metal hits metal. This is "mold protect".
- High-pressure lock-up: the toggle or ram builds full tonnage, applying the Clamp Force / Tonnage that holds the mold shut against injection pressure.
Why it matters
- Mold protection prevents expensive damage: if a part did not eject, the low-pressure phase senses the resistance and stops instead of crushing the tool.
- The speed profile trades cycle time against safety — too aggressive a close risks the mold, too slow wastes time.
- Only after lock-up do the Injection Stages begin.
Related terms
- See also: Clamp, Clamp Force / Tonnage, Molding Cycle, Injection Stages, Part Ejection
What is clamp close in injection molding?
It is the cycle stage that closes and locks the mold before injection, in three phases — fast approach, slow mold-protection, and high-pressure lock-up to full tonnage.
What is mold protection during clamp close?
A low-pressure, slow phase just before the mold touches, so the machine can sense an obstruction (an unejected part or insert) and stop before damaging the tool.
What happens after clamp close?
Once full clamp tonnage is reached, the injection stages begin — first-stage fill, then pack and hold.