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What Does Blanchard Grinding Mean?
Blanchard grinding or rotary surface grinding is one of the oldest types of mechanical grinding. It involves using Blanchard grinders (vertical spindle that drives a horizontally rotating grinding wheel) to remove stock of desired depth from a workpiece with irregular shape or large pieces, ensuring precision, a high degree of flatness, and quality surface finishes. It works well with metals (ferrous and non-ferrous) and plastics. This specialized process derives its name from the Blanchard Machine Company, which developed and patented this efficient machine.
Blanchard grinders are available in various sizes and can achieve accurate flatness and superior finishes. These grinders are suitable for single- or double-sided grinding of workpieces with flat surfaces, preparing them for further machining or finishing. Large stampings, plate stock, large castings, and tool and die are typical components that undergo Blanchard grinding.
Working Principle of Blanchard Grinding
Blanchard grinding is a robust secondary process that relies on a horizontally oriented abrasive wheel propelled by a vertically oriented spindle for precise material removal from a metal workpiece. The workpiece or blank is often fixtured to the work table either mechanically or magnetically during Blanchard grinding.
The work table rotates once the workpiece is in place, and the grinding wheel lowers onto the workpiece to gradually remove the material. The grinding wheel and the table rotate in opposite paths, creating a signature cross-hatched surface appearance on parts that undergo Blanchard grinding. The grinding wheel touches the blank continuously until the desired dimensions and surface properties are achieved. The ability of this process to create precise surfaces on large surface areas and the ease of loading and unloading the parts make it an economical and efficient method.
Reasons for Choosing Blanchard Grinding
Blanchard grinding offers extensive benefits that make it a cornerstone of industrial manufacturing. Here are some of the expected benefits of choosing Blanchard grinding:
Efficient Stock Removal
Blanchard grinders can efficiently shear stock from one side of the material with a broad surface, making it a suitable technique for quickly reducing excess stock and achieving the preferred flatness or thickness.
Smooth Transformation of Parts
This grinding technique ensures consistent and even material removal across large surfaces about 12 feet wide or smaller sections to fill the work table. It guarantees precise flatness and parallelism necessary for rapidly transforming tough materials into usable end-products.
Ideal for Large Surfaced Material
Machinists often handle parts with large, flat surfaces using the Blanchard grinding method because grinders are available in various sizes. The grinding wheel’s rotary action can handle large part sizes easily and maintain uniform grinding across the material’s entire surface.
Excellent Surface Finish
Blanchard grinding offers a distinctive cross-hatch pattern, giving a superior surface finish that is aesthetically appealing and provides functional benefits to applications that demand precise contact surfaces.
Limitations of Blanchard Grinding
Blanchard grinding poses several setbacks, including:
Not Compatible with All Materials
Experts advise against using Blanchard grinding for non-ferrous metals like titanium, aluminum, or brass. It may attract more cost because it requires designing and fabricating custom fixtures that hold the workpiece in place. The design and creation of these custom fixtures make the process less cost-effective and time-consuming. Furthermore, softer materials with generally low machinability ratings and thermoplastics are not ideally compatible with Blanchard grinding.
Limited to Flat Surface Areas
Since the workpiece can only maintain a parallel position with the grinding wheel, the process cannot work on the non-flat geometry. Machinists often use alternative techniques like CNC machining, cylindrical grinding, or surface grinding on angled or curved surfaces and parts to achieve preferred tolerances and finishes.
Thermal Damage to Workpiece
The Blanchard grinding method exposes the workpiece to heat due to the heat occurring from the friction between the part and the grinding wheel. The generated heat can result in thermal distortion in the workpiece, influencing the dimensional accuracy, parallelism, and flatness. This challenge is common when grinding thin materials because the generated heat can pass through the material faster. However, you can mitigate heat generation with adequate use of cooling fluid.
Precision Grinding vs. Blanchard Grinding: What’s their Difference
As its name implies, precision grinding is an efficient process for removing material from relatively small workpieces that demand a high degree of flatness, parallelism, or finish. Machinists often use this technique to repair used parts or make a new component that meets factory specifications. Precision grinding typically works well with coated material and can achieve a superior surface finish of up to 10 RMS.
Machinists grind flat surfaces with an abrasive wheel rotating at incredibly high speeds in horizontal spindle surface grinding. Also, cylindrical grinding removes large amounts of material from round objects using an abrasive wheel rotating at greater speeds and requires different work-holding devices from horizontal spindle surface grinding. Other precision grinding methods include centerless grinding, creep-feed grinding, and internal diameter grinding.
In contrast, Blanchard grinding is more economical than precision grinding. It is ideal for grinding a workpiece with a large surface area and can provide a tolerance of about ±0.001” (0.0254mm). Blanchard grinding can achieve surface finishes up to 65 RMS and produces a unique grinding mark that is often aesthetically appealing.
The machinist holds larger ferrous material with flat magnetic chucks while grinding. The grinding method is also compatible with various non-ferrous materials held in place with alternative types of holding devices.
Conclusion
Blanchard grinding is a crucial finishing process with an unsurpassed ability to provide superior-quality components for numerous applications. It offers precision and versatility in handling large and heavy workpieces to achieve tight tolerances, high quality, and aesthetically appealing surfaces on various large or small parts.
AT-Machining is a reputable CNC machine shop with machining capabilities and modern technology to meet the demands of your grinding project. We specialize in advanced Blanchard grinding processes with state-of-the-art equipment to achieve precision large-surfaced parts with more aesthetic appeal. Contact us today for professional experience whether you are new to the process or have hands-on experience operating a Blanchard grinder!
