Bar stock
This article needs additional citations for verification. (October 2015) |
Bar stock, also (colloquially) known as blank, slug or billet,, angle stock and objects with varying diameter are not considered bar stock.
Bar stock is commonly processed by a sequence of sawing, turning, milling, drilling and grinding to produce a final product, often vastly different from the original stock. In some cases, the process is partially automated by specialized equipment which feeds the stock into the appropriate processing machine.
Process and types
This section possibly contains original research. (October 2015) |
Most metal produced by a
In a
A machine shop typically has a storage area containing a large variety of bar stock. To create a metal component, a bar of sufficient volume is selected from storage and brought to the machining area. This piece may then be
The not-yet-cut bar protruding from the back of the spindle, rotating quickly, can present a safety hazard if it is sticking out too far and unconstrained from bending. Thus sometimes long bars must be sawn into shorter bars before being fed as "bar work" (which is the term for such work).
CNC lathes and screw machines have accessories called "bar feeders", which hold, guide, and feed the bar as commanded by the CNC control. More advanced machines may have a "bar loader" which holds multiple bars and feeds them one at a time into the bar feeder. Bar loaders are like magazines for part blanks (or pallets for milling work) in that they allow lights-out machining. The bar loader is filled with bars (or the magazine or pallet with part blanks) during working hours, and then it runs during the night unattended. Given that there is no human around to detect if something went wrong and the machine should stop, there are various kinds of sensors that are used to detect this, such as load meters, infrared beams, and, in recent years, webcams, which are placed inside the machine tool's enclosure and allow remote viewing of the cutting action.
Uses of bar stock
Bar stock is widely used in many industries and can be seen in many different industrial processes. These processes include forging, extrusion, machining, and many more. In forging, billets are heated to high temperatures before a press pushes the workpiece into the shape on the die. These presses operate at very high forces to make the desired changes to the product. Extrusion uses rollers that push the heated bar stock through a set of dies which will determine the shape of the workpiece. Machining is a subtractive process that utilizes bar stock and various cutters and tools to make intricate details that are not possible through other processes.[2]
Standard sizes throughout a supply chain
To
Sometimes it is necessary that the bar not be very much larger than the intended part, because the metallurgical properties of some metal alloys in some finishing processes may vary by how far inside the bar the metal lies. Thus an engineering drawing will specify a certain size (or a maximum size) that the bar may start out as. These specs face the aforementioned limitation of stocking sizes versus custom mill runs; standard sizes are used wherever possible to avoid wasted expense and needless delays.
Drill rod
A drill rod is
|
|
|
|
Drill blanks have an undersize tolerance of +0/−0.0002 in (0.00508 mm), while reamer blanks have an oversize tolerance of −0/+00.0002 in (0.00508 mm).
Some mills also sell square stock that is held to the same tolerances under the name "drill rod".[3]
Commonly available material grades in the U.S. are A2, D2, M2, M42, O1, S7, W1, and
Ground flat stock
Ground flat stock is
Some geometrical sizes are known as gauge plate.[8]
See also
References
- ^ Brafield, Evans (February 2009), What's Billet?, archived from the original on February 22, 2010, retrieved March 5, 2010.
- ^ Altan, Taylan; Ngaile, Gracious; Shen, Gangshu, Cold and Hot forging: Fundamentals and Applications 1 (1 ed.), ASM International
- ^ ISBN 978-0-07-136076-0.
- ^ McMaster-Carr catalog (115th ed.), McMaster-Carr, pp. 3641–3653, retrieved 2010-12-19.
- ISSN 0032-4558
- ^ Starrett catalog 32 (PDF), p. 624, archived from the original (PDF) on 2011-03-22, retrieved 2010-12-22.
- ^ Starrett catalog 32 (PDF), p. 634, archived from the original (PDF) on 2011-03-22, retrieved 2010-12-22.
- ISBN 978-1-85617-494-7.