Engineering:Dead-blow hammer
 | This article needs attention from an expert in Physics. The specific problem is: Need explanation of physical principles of operation. (July 2015) |
 Dead-blow hammer | |
| Other names | Dead-blow mallet |
|---|---|
| Classification | Hammer |
| Related | Rubber mallet |
A dead-blow hammer is a specialized mallet helpful in minimizing damage to the struck surface and in controlling striking force, with minimal rebound from the struck surface. The minimal rebound is helpful in avoiding accidental damage to precision work, especially in tight locations and in applications such as maintenance work on hydraulic cylinders.
Description
The head of the dead-blow hammer can be solid or hollow (often partially filled with loose steel shot), which distributes the energy of the strike over a longer period of time and reduces rebound.[1]
Solid-head dead-blow hammers are usually made of rubber or resilient plastic (such as polyurethane or ultra-high-molecular-weight polyethylene) and rely on the inherent properties of the material to absorb shock and reduce rebound. Composite heads and fiberglass handle models are also available, with optional shock-absorbent rubber grips. A variant design omits the handle entirely; the dead-blow head is gripped directly in the hand, for use in tight locations.
Some dead-blow hammers have replaceable striking faces, attached by screwing or pressing them into place on the main body of the hammer. These replaceable faces or “inserts” can extend the life of the tool, and can also be hardness matched to the surface being struck, minimizing damage while allowing optimal energy transfer on impact.
Principle of operation
In a conventional solid-head hammer, the momentum of the entire solid mass of the head is delivered in a short period following the moment of impact. A dead-blow hammer delivers the momentum over a longer period, resulting in less peak force, but similar total driving effect for the same head weight.
At the moment the face of the hammer head contacts the surface being struck, the sand or shot within the head is effectively trailing it (Inertia causes it to be collected at the trailing end of the head). The force imparted by this additional loose mass within the head is not imparted to the struck surface at the moment of contact. Instead, this force is spread out over some period of time, as the sand or shot descends to fill the "face" end of the head. Such a blow is less "sharp" than that of the conventional hammer and feels more "dead", presenting less elastic rebound to the user; this is where the hammer gets its name.[1]
Applications
Dead-blow hammers are commonly used in automotive repair for body work, dislodging stuck parts, hubcap installation, and installing and removing knock-off hubs. They also allow controlled use of impact force when performing engine or transmission repair.
In maintenance of hydraulic machinery and aerospace work, dead-blow hammers are useful in freeing stuck cylinders without damaging their precision-formed surfaces or any nearby bearings.
Dead-blow hammers are used in woodworking to knock joints together or apart without denting wood components.[2]
In metalworking, a dead-blow hammer can be used to properly seat the workpiece against parallels in a machine vise.[3][4]
Dead-blow hammers are sometimes used in orthopedic surgical procedures.[citation needed] The tools are also used to shape large diameter telecommunications cables within cable runs.[5]
References
- ↑ 1.0 1.1 "A Guide to Hammers". 2016-06-30. https://www.woodmagazine.com/woodworking-tools/hand/a-guide-to-hammers.
- ↑ Tom Benford (2006). Garage and Workshop Gear Guide. MotorBooks International. pp. 37–. ISBN 9780760323120. https://archive.org/details/garageworkshopge0000benf.
- ↑ Moltrecht, Karl Hans (1981) (in en). Machine Shop Practice, Volume 2. New York, NY: Industrial Press Inc.. p. 22. ISBN 9780831111328. https://books.google.com/books?id=dhX93Mxkxn4C&pg=PA22. Retrieved 3 January 2017.
- ↑ Hoffman, Peter J.; Hopewell, Eric S.; Janes, Brian (2015) (in en). Precision Machining Technology. Cengage Learning. p. 252. ISBN 9781285444543. https://books.google.com/books?id=f9obCgAAQBAJ&pg=PA252. Retrieved 3 January 2017.
- ↑ "Installation Manual for Alloy 825 Sheath Cable Wiring Systems". http://www.pentairthermal.com/Images/EN-PyrotenaxMIindustrialwiring-IM-H57987_tcm432-26199.pdf. Retrieved 13 March 2016.
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