Introduction to the Working Principle of Ball Screws

Because every machine and material is different, you can’t blindly copy exact numbers. Here’s a rule‑of‑thumb rhyme to judge if your back pressure is right: “Smooth charging, no slipping; stable cushion, small deviation. Check the surface for smoke—smooth, bubble‑free, no drooling.” Next time you run into dimensional instability, surface gas marks, or color‑change issues, don’t rush to tweak injection speed. Calm down, look at the back pressure gauge first, adjust back pressure, and the problem that’s been haunting you for days might just solve itself.

This article presents four practical methods for accurately assessing screw wear in extrusion and injection molding machines without disassembly. The methods include melt pressure and position data testing, a pressure drop/backflow evaluation, process reverse deduction through torque and temperature anomalies, and direct borescope inspection. Diagnostic logic linking common symptoms—such as output loss, temperature overshoot, and pressure instability—to specific wear locations is also provided.

the wear-induced failure of screws and barrels, noting the limitations of chrome plating and nitriding. It investigates the feasibility of surface boriding treatment on 45 steel screws and barrels to enhance surface hardness and wear resistance, and validates the process through field testing.

This article introduces the working principle of ball screws, highlighting their high mechanical efficiency and load capacity, which have led to widespread adoption in all-electric servo-driven injection molding machines. It compares ball screw design philosophies for machine tools and injection molding machines, noting that injection units experience loads hundreds to thousands of times greater. Key design priorities for high-load ball screws—such as uniform ball contact pressure, optimized lubrication, and enhanced durability—are discussed, with reference to Ningbo Superior's specialized solutions.

The screw and barrel are the most critical components of injection molding machines, operating under high temperature and pressure. Wear enlarges the clearance between the screw flight and barrel, reducing melting and pumping capacity, causing product quality degradation, lower productivity, and higher energy consumption. The screw is more susceptible to damage than the barrel.