A ball-peen or machinist's hammer, is a type of

peening In metallurgy, peening is the process of working a metal's surface to improve its material properties, usually by mechanical means, such as hammer blows, by blasting with shot ( shot peening), focusing light ( laser peening), or in recent years ...

hammer A hammer is a tool, most often a hand tool, consisting of a weighted "head" fixed to a long handle that is swung to deliver an impact to a small area of an object. This can be, for example, to drive nail (fastener), nails into wood, to sh ...

used in

metalworking Metalworking is the process of shaping and reshaping metals in order to create useful objects, parts, assemblies, and large scale structures. As a term, it covers a wide and diverse range of processes, skills, and tools for producing objects on e ...

. It has two heads, one flat and the other, called the peen, rounded. It is distinguished from a cross-peen hammer, diagonal-peen hammer, point-peen hammer, or chisel-peen hammer by having a

hemispherical A sphere (from Ancient Greek, Greek , ) is a surface (mathematics), surface analogous to the circle, a curve. In solid geometry, a sphere is the Locus (mathematics), set of points that are all at the same distance from a given point in three ...

peen.

Etymology

In the word "ball-peen", ''peen'',. probably comes from a

North Germanic The North Germanic languages make up one of the three branches of the Germanic languages—a sub-family of the Indo-European languages—along with the West Germanic languages and the extinct East Germanic languages. The language group is also r ...

source; compare dialectal Norwegian ("peen"), Danish ("peg"),

German German(s) may refer to: * Germany, the country of the Germans and German things **Germania (Roman era) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizenship in Germany, see also Ge ...

("the peen of a hammer"),

Old Swedish Old Swedish ( Modern Swedish: ) is the name for two distinct stages of the Swedish language that were spoken in the Middle Ages: Early Old Swedish (), spoken from about 1225 until about 1375, and Late Old Swedish (), spoken from about 1375 unti ...

("to pound iron with a hammer").

Uses

Industry during the First World War- Chemical Works Q28206

Besides

(surface-hardening by impact), the ball-peen hammer is useful for many tasks, such as striking punches and

chisel A chisel is a hand tool with a characteristic Wedge, wedge-shaped cutting edge on the end of its blade. A chisel is useful for carving or cutting a hard material such as woodworking, wood, lapidary, stone, or metalworking, metal. Using a chi ...

s (usually performed with the flat face of the hammer). The peening face or ball face is useful for rounding off edges of metal pins and fasteners, such as

rivet A rivet is a permanent mechanical fastener. Before being installed, a rivet consists of a smooth cylinder (geometry), cylindrical shaft with a head on one end. The end opposite the head is called the ''tail''. On installation, the deformed e ...

s. It can also be used to make

gasket Some seals and gaskets A gasket is a mechanical seal which fills the space between two or more mating surfaces, generally to prevent leakage from or into the joined objects while under compression. It is a deformable material that is used to c ...

s for mating surfaces: a suitable gasket material is held over the surface that needs a gasket, and the operator lightly taps around the edges of the mating surface to perforate the gasket material. Peen hammers

Variants

Variants include the straight-peen, diagonal-peen, and cross-peen hammer. Instead of a ball-shaped head, these hammers have a wedge-shaped head. The straight-peen hammer has a wedge oriented parallel to the hammer's handle. The cross-peen hammer's wedge is oriented perpendicular to the handle. The head of a diagonal-peen hammer, as the name implies, has a wedge set at a 45° angle from the handle; it can be a left angle or a right angle, and some peen hammers have a double diagonal wedge for ergonomic reasons. They are commonly used by

blacksmith A blacksmith is a metalsmith who creates objects primarily from wrought iron or steel, but sometimes from #Other metals, other metals, by forging the metal, using tools to hammer, bend, and cut (cf. tinsmith). Blacksmiths produce objects such ...

s during the

forging Forging is a manufacturing process involving the shaping of metal using localized compression (physics), compressive forces. The blows are delivered with a hammer (often a power hammer) or a die (manufacturing), die. Forging is often classif ...

process to deliver blows for forging or to strike other forging tools.

Head materials

Ball-peen hammer heads are typically made of

heat treat Heat treating (or heat treatment) is a group of industrial process, industrial, thermal and metalworking, metalworking processes used to alter the physical property, physical, and sometimes chemical property, chemical, properties of a material. ...

forged Forging is a manufacturing process involving the shaping of metal using localized compression (physics), compressive forces. The blows are delivered with a hammer (often a power hammer) or a die (manufacturing), die. Forging is often classif ...

high-carbon steel Carbon steel is a steel with carbon content from about 0.05 up to 2.1 percent by weight. The definition of carbon steel from the American Iron and Steel Institute (AISI) states: * no minimum content is specified or required for chromium, cobal ...

. or

alloy steel Alloy steel is steel that is Alloy, alloyed with a variety of elements in amounts between 1.0% and 50% by weight, typically to improve its List of materials properties#Mechanical properties, mechanical properties. Types Alloy steels divide into ...

; it is harder than the face of a

claw hammer A claw hammer is a hammer primarily used in carpentry for driving nail (fastener), nails into or pulling them from wood. Historically, a claw hammer has been associated with woodworking, but is also used in general applications. It is not sui ...

. Softer brass heads are sometimes used.

References

Bibliography

* {{Metalworking navbox, tool open Hammers Metalworking hand tools Woodworking hand tools