Techniques for improving the precision of thin parts processed on surface grinders

2025-08-21 06:33:10

01

Types of surface grinding machines and the Challenges of Thin-Wafer Machining

▲ Classification of surface grinders

Surface grinders, as a type of grinding machine, primarily rely on the rotation of a grinding wheel to grind workpieces to the desired flatness. Surface grinders can be categorized into various types, including rectangular, circular, horizontal, and vertical, depending on the worktable shape and shaft type. The worktable shape can be categorized as rectangular or circular, with the primary parameters corresponding to the width and length of the worktable and the diameter of the work surface, respectively. Furthermore, depending on the shaft type, surface grinders can be further divided into horizontal and vertical types.

▲ Challenges of thin film processing

Machining thin parts such as washers, friction plates, templates, and thin plates often presents a series of challenges. Common issues with thin parts include insufficient rigidity, heat dissipation difficulties, deformation during clamping, which affects machining accuracy, bending deformation after heat treatment, clamping deformation caused by the clamping process, and warping during grinding. To address these issues, magnetic chucks are often used for grinding on surface grinders. However, after grinding, the thin workpiece often cannot be restored to its original shape due to the magnetic attraction, thus affecting machining accuracy.

02

Clamping Methods for Improving Thin-Sheet Processing Accuracy

▲ Temporary measures strengthen rigidity

To ensure accurate positioning and clamping of thin workpieces in a free state, and to achieve double-end grinding to meet part precision requirements, the workpiece is bonded to a flat plate using epoxy resin or thick grease to enhance rigidity and prevent clamping deformation. First, the thin workpiece is bonded to a flat plate using epoxy resin, securing the workpiece to the plate in a free state. The plate and workpiece are then placed on a magnetic chuck. After grinding one flat end of the thin workpiece, the workpiece is removed from the plate and attached to the magnetic chuck with only the flattened side. The other flat end is then ground. During this process, the epoxy resin's fluidity allows it to fill the slight gap between the workpiece and the plate. After curing, the workpiece and plate are firmly bonded, significantly improving rigidity. The magnetic force prevents clamping deformation of the thin workpiece, facilitating precise grinding of both flat ends. Alternatively, using thick grease instead of epoxy resin to fill the gap can also enhance rigidity and optimize grinding.

▲ Mechanical clamping method

With the aid of a surface grinder, the workpiece is secured with a flat-nose pliers, the feed rate is gradually reduced, and grinding is repeated until the required flatness is achieved. The thin workpiece is secured to the magnetic table with a flat-nose pliers. Due to the pliers' height, the magnetic force acting on the jaws is relatively small. After grinding one side of the sheet, the feed rate is gradually reduced and the workpiece is removed. The finished surface is then placed back on the magnetic table, and grinding continues on the other side. Repeated grinding continues until both sides meet the desired flatness standard.

▲ Vacuum clamping method

This clamping system utilizes atmospheric pressure and a vacuum clamp to clamp the workpiece, making it suitable for circumferential grinding and ensuring precision. Atmospheric pressure is used to clamp thin workpieces for grinding. The operating principle is as follows: The clamping system is designed with a rubber sealing ring, and the workpiece is placed on the sealing ring, forming a closed chamber. A vacuum pump extracts the air from the chamber through an exhaust port, securing the workpiece in place. Due to its moderate clamping force, it is suitable for circumferential grinding. After grinding one surface, the other surface can be ground in the same manner, achieving the same desired results.

▲ Clamping method of elastic gasket

A rubber gasket is placed between the workpiece and the magnetic table to reduce elastic deformation and achieve precise grinding. When grinding thin workpieces on a surface grinder, an elastic clamping mechanism is used to precisely position and clamp the workpiece without constraints. A 0.5mm thick rubber gasket is placed between the workpiece and the magnetic table. When the workpiece is subjected to magnetic attraction, the rubber gasket compresses and deforms, reducing elastic deformation and allowing the workpiece to be ground flat. After repeated grinding, the desired machining accuracy is achieved.