Ideal for high-cycle (faster cycle time) and thin-wall molding in electric injection molding machines

Achieved highest level of speed and heat-resistance in the industry with newly developed “SRM Recirculation System” and heat-resistant materials and parts

NSK has developed HTF-SRM Ball Screws, a high-speed, heat-resistant version of its high-load drive ball screws, ideal for high-cycle, thin-wall molding in electric injection molding machines.

NSK is exhibiting this product at the IPF Japan 2023 International Plastics Fair and plans to begin accepting orders in April 2024, with a global rollout to follow. NSK aims to achieve annual sales of 500 million yen by fiscal 2026 for this product.

High-Speed, Heat-Resistant HTF-SRM Ball Screws for High-Load Drive Applications

Background

In recent years, demand for plastic products has been on the rise due to an increasing world population and increasing living standards in emerging economies. At the same time, as part of the SDGs and carbon neutral initiatives, there is a growing demand for more environmentally friendly products than ever before.

In line with social and industry trends, electric injection molding machines used to manufacture plastic products require high-cycle performance to improve productivity to meet increasing demand, and the ability to mold thin-wall plastic parts to reduce plastic material consumption and reduce environmental burden.

Against this background, there is demand for high-load drive ball screws for electric injection molding machines that enable higher cycle speeds and thin-wall molding. High-cycle means faster operating speeds that require countermeasures to deal with the accompanying additional heat generation.

Features

The newly developed SRM (Smooth Return Metal coupling) recirculation system and heat-resistant components achieve the industry's highest level of operating speed and heat resistance. The permissible d-n value1 is 200,000, a 40% improvement over NSK's conventional high-speed HTF-SRC ball screws. The maximum operating temperature is 90°C and momentary maximum temperature is 100°C, both of which are 20°C higher than NSK's conventional products.

Interchangeable design: The external dimensions of the screw and nut are the same as those of the HTF-SRC model, eliminating the need for design changes when upgrading.

1 dN value = shaft diameter d (mm) x shaft rotation speed n (min-1)

Technology

1. Newly Developed SRM Recirculation System

One of the technical challenges associated with higher speeds is the higher impact force of ball recirculation, resulting in damage to the recirculation parts and ball screw shaft. We have now completely overcome this issue by applying NSK Digital Twin technology to optimize the recirculation path.

2. Steel Recirculation Components

The SRM Recirculation System is a complex steel shape manufactured with precision machining technology. The result is smooth ball recirculation and improved heat resistance, breaking through the limits of conventional resin (plastic) materials to achieve higher speed and higher heat resistance than ever before.

3. Heat-Resistant Materials

Heat-resistant materials are used for the seals and resin components, and the design has been further improved to enhance heat resistance.