A ball-peen or ball pein hammer, also known as a 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), or focusing light ( laser peening). Peening is norm ...

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 nails into wood, to shape metal (as wi ...

used in

metalworking Metalworking is the process of shaping and reshaping metals 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 every scale ...

. 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 peen.

Uses

Besides for

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

punch Punch commonly refers to: * Punch (combat), a strike made using the hand closed into a fist * Punch (drink), a wide assortment of drinks, non-alcoholic or alcoholic, generally containing fruit or fruit juice Punch may also refer to: Places * Pu ...

es and

chisel A chisel is a tool with a characteristically shaped cutting edge (such that wood chisels have lent part of their name to a particular grind) of blade on its end, for carving or cutting a hard material such as wood, stone, or metal by hand, s ...

s (usually performed with the flat face of the hammer). The peening 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 cylindrical shaft with a head on one end. The end opposite to the head is called the ''tail''. On installation, the rivet is placed in a punched ...

s. The ball face of the hammer 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 ...

s for mating surfaces. A suitable gasket material is held over the surface where a corresponding gasket is desired, and the operator will lightly tap around the edges of the mating surface to perforate the gasket material.

Variants

Variants include the straight-peen, diagonal-peen, and cross-peen hammer. These hammers have a wedge-shaped head instead of a ball-shaped head. This wedge shape spreads the metal perpendicular to the edge of the head. The straight-peen hammer has the wedge oriented parallel to the hammer's handle, while the cross-peen hammer's wedge is oriented perpendicular. The diagonal-peen hammer's head, as the name implies, is at a 45° angle from the handle. 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, by forging the metal, using tools to hammer, bend, and cut (cf. tinsmith). Blacksmiths produce objects such as gates, gr ...

s during the

forging Forging is a manufacturing process involving the shaping of metal using localized compressive forces. The blows are delivered with a hammer (often a power hammer) or a die. Forging is often classified according to the temperature at which ...

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, thermal and metalworking processes used to alter the physical, and sometimes chemical, properties of a material. The most common application is metallurgical. Heat treatments are al ...

forged Forging is a manufacturing process involving the shaping of metal using localized compressive forces. The blows are delivered with a hammer (often a power hammer) or a die. Forging is often classified according to the temperature at which it ...

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, coba ...

alloy steel Alloy steel is steel that is alloyed with a variety of elements in total amounts between 1.0% and 50% by weight to improve its mechanical properties. Alloy steels are broken down into two groups: low alloy steels and high alloy steels. The differe ...

; it is harder than the face of a

claw hammer A claw hammer is a hammer primarily used in carpentry for driving 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 suitable for heavy ...

. Softer brass heads are sometimes used.

Notes

References

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