Flat honing: progress in process measurements | Modern machine shop

Single-sided grinding now offers a more efficient alternative to single-sided grinding and polishing processes. The key is the in-process measurement system, which allows the flat surface honing machine to automatically adjust wheel pressure for consistent results.
Stahli’s FH-602 surface honing machine automates load ring changing for continuous production.
Historically, single-sided grinding operations were performed by grinding and polishing because new abrasives such as silicon carbide, aluminum oxide, or diamond could be added while maintaining constant grinding pressure. This approach allows for a constant removal rate. Matt Huff and Timon Rimi of the team at Stahli Lapping Technologies (Lake Zurich, Ill.) say the use of single-sided abrasive grinding wheels now offers a more efficient alternative.
They explained that honing (finishing) the planetary kinematic plane using cubic boron nitride (cBN) or diamond grinding wheels is possible if variable pressure can be applied to adjust the passivation of the grinding wheel. Without these adjustments, it is not possible to control a surface honing machine simply by setting the grinding cycle time, since the grinding speed will vary depending on the grinding interval of the wheel. Therefore, an in-process measurement system is needed so that the machine control unit can increase the pressure on the part to compensate for the drop in cutting speed. By varying the pressure, you can maintain optimal sharpness of the grinding wheel. This method allows the grinding wheel to sharpen itself, minimizing the rate at which it becomes dull. The newly released Stahli FH-602 machine now provides the high-precision, high-precision measurement system required for this process, these people said.
They added that Stahli Lapping Technologies offers grinding processes on the FH-602 series, which is similar to DLM’s larger series of production machines. This development allows customers to perform complex and delicate operations on their machines. They say consistent results can be achieved without any sharpening for 30 to 100 passes, depending on stock removal and surface finish requirements and consumables used.
The FH-602 uses an automatic dimensional control system from SPS Industries (Farmington, CT) with a touch screen to enter and adjust process parameters. A grinding program can be defined as a series of steps in which the grinding force or removal rate can be controlled by a freely selectable grinding wheel speed. Mr. Huff and Mr. Rimi noted that the pressure block has been developed and optimized over many generations and is one of the most important parts of the system. It contains an online system with micron accuracy to measure the thickness of the part between the table and the grinding wheel. The continuously variable drive motors for the rings and pressure plates are also located here. A variety of hard and soft pressure plates are available to adapt to different workpiece materials.
Each batch of parts is placed in a carrier tray, which holds the parts inside a loading ring. One ring with the loading plate is ground at the same time, and the other ring can be prepared outside the machine. The rings of finished and unfinished parts can be changed manually or automatically, depending on how the machine module design is configured. Versions of this machine are available with a full coating station for manual loading, as well as with a stripping machine for integration into automated cells.
According to Mr. Huff and Mr. Rimi, another important feature of the FH-602 series is the automatic sharpening and dressing station. It is located at the rear of the machine, opposite the grinding station. The sharpening and rinsing sequence can be started manually or automatically after a certain number of cycles or when a specified sharpening time per cycle has been reached. They also note that diamond and cubic boron nitride wheels can be used for single-sided flat surface honing using planetary kinematics combined with precise process measurements. The efficiency of these super abrasive wheels enhances the process and adds new manufacturing applications.
With so many options for 5-axis machining technology, how do you know which one is best for your shop? Let’s look at the details first. Then look at existing processes and the potential benefits of the five axes.
One potential cause of serious injury during grinding involves a simple mistake: operating the grinding wheel at too high a speed.

Post time: Sep-18-2023

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