Questions You Should Know about difference between cylindrical and surface grinding

Grinding machine

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The cylindrical grinder is a type of grinding machine used to shape the outside of an object. The cylindrical grinder can work on a variety of shapes, however the object must have a central axis of rotation. This includes but is not limited to such shapes as a cylinder, an ellipse, a cam, or a crankshaft.[1]

A cylindrical grinder.

Cylindrical grinding is defined as having four essential actions:

1. The work (object) must be constantly rotating
2. The grinding wheel must be constantly rotating
3. The grinding wheel is fed towards and away from the work
4. Either the work or the grinding wheel is transversed with respect to the other.

While the majority of cylindrical grinders employ all four movements, there are grinders that only employ three of the four actions.[1][2]

History

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The origins of the cylindrical grinder, as with all other modern machine tools, stem from the experimentation and invention of John Wilkinson and later Henry Maudslay who built the first horizontal boring machine and the first engine lathe, respectively. The cylindrical grinder owes much of its development from the onset of the Industrial Revolution, particularly to the advent of reliable, inexpensive steel production and later the improvement of the grinding wheel.[1] The basis for the modern day cylindrical grinder was first built in the s by two men working independently, Jonathan Bridges and James Wheaton . It is unclear as to which man had first produced the machine but both are closely tied to the first historical appearance of the modern day tool. It took another 40 years before further improvement and refinement of the tool occurred.[3]

The Brown & Sharpe company in Providence, RI was one of the first builders of the Willcox & Gibbs Sewing Machine, one of the first piece of precision machinery to be used in a residential setting. Joseph Brown believed that the shaft and needle bars of the sewing machine must be crafted from hardened tool steel. It was this desire that led to their experimentation with building a cylindrical grinder. The first attempt was simply a small lathe with a grinding wheel mounted to it. Subsequent attempts led to the cylindrical grinder displayed at the Centennial Exposition and the subsequent patent.[1][3]

It is important to note that Brown & Sharpe cannot be given sole credit of pioneering advances in cylindrical grinding. A man in Waltham, Massachusetts, Ambrose Webster had created a small grinding machine in that contained all of the improvements Brown & Sharpe claimed to be their own original invention. Even more so, the emphasis on precision, accuracy, and reliability was championed by Charles Norton.[4]

Norton was an employee of Brown & Sharpe who quit the company with the desire to further pursue his belief that the cylindrical grinder is not merely a finishing tool but could be a staple of the machine shop. He founded the Norton Grinding Company, where he continued improving the cylindrical grinder to use faster rpm values and more precise grinding tolerances. He was acknowledged for his work on April 18, when he won The John Scott Medal and Premium for his invention of "accurate grinding devices of high power". These standards developed by Norton were the status quo until about the middle of the 20th century.[4]

The remainder of technological innovation applicable to the cylindrical grinder is almost identical and entangled in a sense, to the rest of machine tools. The innovation of the last 70 years can be characterized by three waves of change.[5] The first wave was the creation of numerical control by John T. Parsons in the s. The U.S. Air Force, looking for a faster, cheaper, and more efficient means of part and tool production for airplanes, played a large role in developing NC both politically and financially. The first implementation of NC in machine tools occurred in the s and continued through the s.[5] The second wave of innovation, occurring during the s and s, is marked by the massive demand for microcomputers to be used to direct NC.[5] The joining of computers marked the birth of Computer Numerical Control which once again revolutionized the ability of the cylindrical grinder. Now the machine was able to receive instruction from a computer which would give it precise directions on every imaginable dimension and measurement needed to produce the desired product. This was a completely different work environment in comparison to mid-century production where a worker had to direct the machine at every point on how to manipulate the work. The third wave of change came in the s with the advent of the Personal Computer. Integrating CNC and the PC into one dynamic system allowed for even further control of the manufacturing process that required little to no human supervision.[5]

Methods

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Outside Diameter Cylindrical Grinding Inside Diameter Cylindrical Grinding

There are five different types of cylindrical grinding: outside diameter (OD) grinding, inside diameter (ID) grinding, plunge grinding, creep feed grinding, and centerless grinding.[6]

Outside diameter grinding

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OD grinding is grinding occurring on external surface of an object between the centers. The centers are end units with a point that allow the object to be rotated. The grinding wheel is also being rotated in the same direction when it comes in contact with the object. This effectively means the two surfaces will be moving opposite directions when contact is made which allows for a smoother operation and less chance of a jam up.[7]

Inside diameter grinding

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ID grinding is grinding occurring on the inside of an object. The grinding wheel is always smaller than the width of the hole being ground. The object is held in place by a collet, which also rotates the object in place. Just as with OD grinding, the grinding wheel and the object are rotated in opposite directions giving reversed direction contact of the two surfaces where the grinding occurs.[7] See also ID Grinding.

Plunge grinding

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A form of OD grinding, however the major difference is that the grinding wheel makes continuous contact with a single point of the object instead of traversing the object.[8][6]

Creep feed grinding

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Creep Feed is a form of grinding where a full depth of cut is removed in a single pass of the wheel. Successful operation of this technique can reduce manufacturing time by 50%, but often the grinding machine being used must be designed specifically for this purpose. This form occurs in both cylindrical and surface grinding.[6]

Centerless grinding

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Centerless cylindrical grinder A schematic of the centerless grinding process.

Centerless grinding is a form of grinding where there is no collet or pair of centers holding the object in place. Instead, there is a regulating wheel positioned on the opposite side of the object to the grinding wheel. A work rest keeps the object at the appropriate height but has no bearing on its rotary speed. The workblade is angled slightly towards the regulating wheel, with the workpiece centerline above the centerlines of the regulating and grinding wheel; this means that high spots do not tend to generate corresponding opposite low spots, and hence the roundness of parts can be improved. Centerless grinding is much easier to combine with automatic loading procedures than centered grinding; through feed grinding, where the regulating wheel is held at a slight angle to the part so that there is a force feeding the part through the grinder, is particularly efficient.[9]

Control methods

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There are three basics ways in which an operator can interact with a cylindrical grinder. Either manual manipulation of the machine, Numerical Control with a punched card system or using Computer Numerical Control using a pre existing interface designed for that machine or by using a PC as an interface to communicate with the grinder. The first two options are rarely if ever used today. CNC operated cylindrical grinders are the most technologically advanced, efficient, reliable systems in the manufacturing industry.[7]

Applications

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Cylindrical grinders, versatile and precise machines, are employed in various industries for a range of applications due to their capability to achieve fine finishes and tight tolerances on cylindrical surfaces. These applications include:

1. Automotive Industry: Utilized for manufacturing engine components, transmission components, and other critical parts, where precision is paramount for performance and safety.

1. Aerospace: Essential in producing engine and turbine components, bearings, landing gear, and hydraulic control valves, demanding high precision for reliable aerospace operations.

1. Medical Devices: Employed in the creation of surgical tools, prostheses, and dental equipment. The precision grinding is crucial for the functionality and safety of medical devices.

1. Energy Industry: Used for manufacturing rotor shafts, transmission components, and compressor components, particularly where tough materials require precise machining.

Cylindrical grinders are adaptable to various materials and can handle different cylindrical shapes, proving indispensable in industries requiring high-precision grinding.

See also

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References

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Surface grinding and cylindrical grinding are two common grinding methods used in manufacturing processes. Here are the main differences between the two:

1. Object shape: Surface grinding is used to grind flat surfaces, such as metal sheets, plates, or any other material with a flat geometry. Cylindrical grinding, on the other hand, is used to grind cylindrical or round objects, such as rods, shafts, or cylindrical workpieces.

2. Grinding wheel shape: In surface grinding, a horizontal spindle with a grinding wheel is used, which is generally a flat or cup-shaped wheel. In cylindrical grinding, a cylindrical grinding wheel is used, which has a cylindrical shape.

3. Grinding operation: Surface grinding involves the grinding wheel moving across the surface of the workpiece in a linear fashion, removing material from the surface to achieve the desired shape or finish. Cylindrical grinding, on the other hand, involves the rotation of the workpiece while the grinding wheel moves back and forth along the length of the workpiece to remove material and create a cylindrical shape.

4. Workpiece holding: In surface grinding, the workpiece is typically held in a magnetic chuck or a vice, ensuring it remains stationary during the grinding process. In cylindrical grinding, the workpiece is typically held between centers or in a chuck, allowing it to rotate during the grinding process.

5. Applications: Surface grinding is commonly used for finishing flat surfaces, removing stock material, or achieving high surface quality and accuracy. Cylindrical grinding is often used for machining cylindrical or round objects to achieve precise dimensions, roundness, or surface finishes.

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