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How to solve the accuracy deviation of the mold opening position in a plastic injection molding machine?

2025/11/21 By le zhan

Plastic Injection Molding Machine 10-8

When the mold opening position of a plastic injection molding machine deviates by 3 mm per cycle, it causes flash (excess plastic) on precision parts, rendering them unusable. In industries such as medical, automotive, or electronics, part tolerances can be as small as ±0.5 mm, and even a 1 mm deviation can have serious consequences. To better address this issue, Topstar employs a new inclined elbow layout to accommodate extra-large mold openings, achieving mold opening position accuracy of less than +1 mm and ensuring rapid, stable mold movement.

What is Mold Opening Position Accuracy Deviation in Plastic Injection Molding Machine?

To solve the problem of mold opening position accuracy deviation, it’s essential to understand what it is and why it’s crucial. Simply put, mold opening position accuracy deviation is the failure of the moving platen of a plastic injection molding machine to stop at the target position in each cycle precisely. Deviations can range from 0.5 mm to 5 mm—regardless of size, they will interfere with the molding process.

If the platen stops too short (insufficient opening), the mold cannot wholly separate, leading to parts sticking or tearing. If the pressure plate stops too far (opening too large), misalignment can occur during mold closing, leading to flash, warping, and even mold damage. Therefore, for precision parts, even a 1mm deviation can cause dimensions to exceed tolerances. Mold opening accuracy is fundamental to ensuring stable part quality; if the pressure plate doesn’t stop at the correct position, every step from injection molding to cooling will be affected.

Flash, warping, and even mold damage during injection molding.

Why do traditional mold opening mechanisms fail?

Traditional plastic injection molding machines rely on outdated toggle or hydraulic-cylinder layouts, making it challenging to guarantee accuracy—especially in large molds or high-volume production. Uneven force distribution occurs, and the old toggle mechanism design applies uneven pressure to the moving pressure plate, causing it to “wobble” during opening and closing. This wobbling leads to inconsistent stop positions. Furthermore, limited adjustability means most traditional injection molding machines cannot accommodate ultra-large molds. The pressure plate movement becomes unbalanced, leading to increased deviations.

Additionally, wear-induced drift occurs; sliding guides and hydraulic components wear over time, causing system gaps. Even slight wear (0.1 mm) can lead to significant deviations. Furthermore, their slow response time—hydraulic systems requiring 5-10 milliseconds to adjust position—is too slow to correct deviations during cycles.

The Hidden Costs of Mold Opening Deviations in Plastic Injection Molding Machines

Mold opening position accuracy deviations not only cause scrap but also impact the entire production process, increasing production costs. Scrap and rework are the most obvious costs. A consumer electronics mold manufacturer in Texas calculated that parts scrapped due to a 2 mm deviation waste 220 pounds of resin per month—a material fee of $3,300 alone. Reworking repairable parts requires an additional 8 hours of labor per week.

Additionally, mold damage can lead to misalignment during mold opening, causing wear on the mold cavity, core, and guide pins. Custom molds cost between $50,000 and $200,000, and deviations can shorten their lifespan by 30% to 40%. It also results in excessive downtime, with operators frequently needing to stop production to adjust the machine, recalibrate, or repair stuck molds.

The Hidden Costs of Mold Opening Deviations in Plastic Injection Molding Machines

New Inclined Row Machine Layout Toggle – A Solution for Precision < +1mm

To address the issue of mold opening position accuracy deviation, Topstar has designed a new inclined row layout for the machine toggle. This layout allows for more even force distribution across the moving platen, eliminating wobbling. Every point on the platen moves in perfect synchrony, ensuring a consistent stopping position every time. Simultaneously, it allows for greater adjustability of ultra-large molds. Unlike traditional toggle structures, this inclined elbow layout can accommodate molds up to 3 meters in length. It uses an adjustable elbow angle to balance platen movement, enabling effective operation even with ultra-large or asymmetrical molds.

In Topstar’s tests, this layout achieved mold opening positioning accuracy of less than ±1 mm, far exceeding the industry average of ±2mm. This level of accuracy meets the most stringent tolerance requirements. The rigid structure of the elbow reduces vibration during opening and closing, shortening the cutting cycle time by 5-8% and enabling fast, stable movement in plastic injection molding machines.

New Inclined Row Machine Layout Toggle – A Solution for Precision +1mm

Maintenance Tips for Maintaining Mold Opening Accuracy

Even with Topstar’s inclined row machine toggle layout, proper maintenance can ensure your plastic injection molding machine maintains an accuracy of <+1mm for years. Lubricate the elbows quarterly with Topstar’s recommended grease to keep the moving parts running smoothly. Dry joints can cause friction and deviation. Also, check the linear guides monthly and wipe them clean to remove dust and debris. Inspect for wear and replace if necessary. Utilize monitoring cycle data; Topstar injection molding machines record mold opening position data. Review this data weekly to identify trends (e.g., gradual deviation). Address problems early to avoid costly downtime.

Completely Solve Mold Opening Deviation Problems

Mold opening position accuracy deviation in injection molding machines no longer needs to be a long-term problem. Topstar’s angled elbow layout design in plastic injection molding machines effectively eliminates deviation through uniform force distribution, a wide mold adjustment range, and an accuracy of less than +1mm, ensuring that every part meets tolerance requirements in every production cycle.

 

 

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