Servo Valves for Shot Mass Repeatability and Scrap Reduction in Injection Molding
In injection molding, part consistency is critical, as small variations can quickly turn into scrap. Scrap rate directly impacts both material cost and profitability.
How Shot Mass Consistency Depends on Hydraulic Control Performance
Shot mass is the amount of molten plastic injected into the mold during each cycle. It is a critical quality factor in injection molding because the mold cavity has a fixed volume. If shot mass varies from cycle to cycle, the cavity underfills or overpacks. This is why having stable control gives you complete fill, consistent part weight, and reliable part quality.
Maintaining stable shot mass is essential for complete cavity fill, consistent part weight, and repeatable part quality. Variability typically comes from:
Servo valves help improve this repeatability by precisely regulating hydraulic flow and pressure to the injection unit, so the machine can follow its programmed injection profile more accurately from shot to shot. This tighter control stabilizes melt delivery. In high-volume or tight-tolerance molding, even small shot mass variation quickly turns into scrap, rework, or lost capacity.
Why servo valves are the right approach
Low weight reduces stress on manifolds and moving assemblies, helping the mounting stay aligned and stable over millions of cycles. Over time, that mechanical stability supports more consistent shots and fewer surprises in part quality.
High bandwidth and low hysteresis work together to hold and constantly correct injection speed and pressure during the cycle. The valve tracks the command profile closely, which cuts variation in part weight, dimensions, and surface quality and decreases scrap rates. These behaviors show up in high-pressure die casting, where unstable flow and clamp timing cause flash, porosity, and scrap.
Fast step response ensures a clean, repeatable transition from filling the mold to packing the material tight. Pressure is applied at the correct time and level every cycle, which helps prevent flash, short shots, and other defects tied directly to poor pack timing. Rubber injection molding uses the same fast, repeatable control to improve shot consistency, cure quality, and overall part reliability.