Precision Grinding Techniques
The term “precision grinding” refers to several techniques—all of which employ the same basic methods: Abrasive tools are used to produce a clean surface, modify a form and/or reduce thickness. There are important differences, however, which we’ll address here.
Precision grinding, as its name suggests, produces perfectly fabricated workpieces by incrementally removing material to create utmost accuracy and, typically, superior surface finishes. Precision grinding machines can provide tolerances of +/- 0.0001, on a daily basis, and even better at times.
Precision grinding involves a cylindrical grinding tool (a wheel) covered with abrasive material rotating against the surface of the workpiece at a set degree of force. The process removes as little material as possible to achieve the required results. Differing sized wheels and abrasive materials are used, depending on the workpiece’s makeup.
Any metal and many types of plastics, resins and composites can be finished using precision grinding equipment. Industries commonly requiring these services include aerospace, automotive, motion control and transportation.
Honing is a final finishing operation conducted on a surface, typically the inside diameter, with minimal stock removal. Slight, uniform pressure is applied to a light abrasive that wipes over the surface. Abrasive stones remove trace amounts of material to tighten the cylindricity tolerance.
Lapping removes material slowly and typically is used in smoothing, finishing and achieving an extremely close tolerance on metal surfaces. A lapping compound is rubbed against the workpiece in rotary and reciprocating motion, producing a smooth but not shiny surface.
Thread grinding involves the process of cutting or finishing threads on a workpiece by using specially designed grinding wheels. The process is used for cavities, ball screws, core pins (electrodes), medical bone taps and worms most commonly in the following industries: aerospace, EDM, medical, motion control, plastics and tooling.
Cylindrical grinding is one of the most common processes, used mainly for grinding rotationally symmetrical workpieces. Common applications include: shafts, rollers, bearing journals, mandrels, cores. Cylindrical grinding also is used to taper and contour workpieces.
Centerless grinding differs from other cylindrical processes because the workpiece is not mechanically constrained. Centerless grinding is used to achieve roundness, surface finish and dimensional tolerances that are among the best available in metalworking.
Rotary Surface Grinding
Rotary surface grinding, also known as Blanchard grinding, is highly effective at smoothing and grinding large, flat surfaces—and is the option for efficiently removing large amounts of material when not looking for a high degree of finish. It doesn’t mean, however, that Blanchard grinding is lesser at achieving results. When properly done, Blanchard grinding techniques achieve comparable tolerances to more refined grinding methods.
The process employs a horizontal grinding wheel (called a “segment” in these machines), a vertical grinding spindle and a magnet or other holding component to stabilize the part. As the table rotates, the unfinished part comes into contact with the grinding segments, also rapidly rotating, removing material in two directions. This creates a distinctive cross-hatch pattern on the surface.
Blanchard grinding can modify ferrous and non-ferrous materials, with different options in magnets and other holding components to match the type of material being processed. Blanchard grinding is highly effective at removing large amounts of material.
Precision grinding techniques all accomplish the same basic function. Which method used is determined by workpiece requirements.
Minnesota Grinding is highly equipped to handle production demands, with extensive experience completing projects using an array of materials and complex designs. From design to prototype to final production runs, we offer comprehensive services for businesses across many industries, including: aerospace, automotive, manufacturing, motion control, transportation, agriculture and heavy equipment.
Our 43,000-square-foot facility has the capacity and capabilities to complete large and small projects. Our goal is to offer comprehensive grinding services to complete entire workpieces under one roof. Interested in learning more? Call us for more details at (763) 535-4445 or request a quote.