Every Shot Leaves a Signature
What the shot curve records
A shot monitoring system plots plunger position, velocity and hydraulic pressure against time. The curve divides into the slow shot that closes the shot sleeve, the fast shot that fills the cavity, and the intensification phase that compacts the metal as it solidifies.
Each segment has a target window. When metal level, die temperature or sleeve condition drifts, the curve shape drifts with it, often before castings show visible defects.
Common signatures and what they mean
A slow-shot spike usually indicates a wave of air pushed down the sleeve, a sign of poor metal dosing that feeds porosity. A fast-shot velocity below target suggests cold metal or a worn plunger tip leaking past. Weak intensification rise points to leakage or valve problems that reduce compaction pressure.
Because these signatures repeat shot after shot, statistical limits on curve parameters catch process drift early.
From monitoring to control
Modern machines reject or flag shots outside set limits automatically. The practical discipline is simpler: record every shot, alarm on drift, and tie shot data to downstream inspection results so parameters can be tuned with evidence.
Shot data also helps after a die change. Comparing curves across tools and alloys builds a reference library that shortens setup time and preserves what worked last run.
FAQ
What is the shot curve in die casting?
It is the recorded trace of plunger position, velocity and hydraulic pressure during one injection, covering the slow-shot phase, fast shot and intensification.
Why monitor intensification pressure?
Intensification compacts the solidifying metal and directly affects shrinkage and porosity. A weak or slow pressure rise signals hydraulic leakage or valve issues that degrade quality.
How does shot monitoring reduce scrap?
Curve signatures drift when metal level, temperature or machine condition drift. Alarming on those parameters catches process drift before defective parts are produced in volume.
Is shot monitoring worth it on older machines?
Yes. Retrofit monitoring kits exist for many legacy machines, and the shot curve is often the earliest available signal of process change.
All figures above refer to standard product data sheets; final confirmation is subject to written quotation.