mahogany stick

See spotting stick.

map

A simplified detail print or sketch usually showing just the location and sizes of holes in a detail or steel.

marforming process

A rubber-pad forming process developed to form wrinkle-free shrink flanges and deep-drawn shells.  It differs from the Guerin process in that the sheet metal blank is clamped between the rubber pad and the blankholder before forming begins.

marriage gap

Space between the trim edge of the inner panel and the inside of metal of the outer panel flange before hemming. (See Figure M1)

master

(1) Lower section of a die on which the part nests.  Also called a master plug, adapter, boss, die post, horn, locator, and stool.

(2) Section of die used to govern the form or contour of the mating die section.  Usually male shape or inside metal.

(3) Wood model or die aid.

match

A condition in which a point in one die half is aligned properly with the corresponding point in the opposite die half within specified tolerance.

mating flange area

Area of inner panel covered by flange of outer panel.

mating surface

Area of inner panel that is in contact with outer panel. (See Figure M2)

maximum elongation

It is the maximum engineering strain the material can take until fracture.  Also called fracture strain.  Shown as e_max. (See Figure M3)

mechanical press

A forging press with an inertia flywheel, a crank and clutch, or other mechanical device to operate the ram.

mechanical press brake

A press brake using a mechanical drive consisting of a motor, flywheel, crankshaft, clutch, and eccentric to generate vertical motion.

mechanical working

The subjecting of material to pressure exerted by rolls, hammers, or presses in order to change the shape or physical properties of the material.

metal clearance

“ Depending on stock thickness being used to make the part in the die, it is the running clearance on bottom of press stroke between flange steels or male and female form steels.” (Automotive Steel Partnership, 1991, p. 11).

metalworking

See forming.

midget mill

See carburr.

mill

(1) A factory in which metals are hot worked, cold worked, or melted and cast into standard shapes suitable for secondary fabrication into commercial products. (2) A production line, usually of four or more stands, for hot or cold rolling metal into standard shapes such as bar, rod, plate, sheet, or strip. (3) A single machine for hot rolling, cold rolling, or extruding metal; examples include blooming mill, cluster mill, four-high mill, and Sendzimer mill. (4) A shop term for a milling cutter. (5) A machine or group of machines for grinding or crushing ores and other minerals.

mill edge

The normal edge produced in rolling.  Can be contrasted with a blanked or sheared edge which has a burr.

mill finish

without being subjected to a special surface treatment (other than a corrosion-preventive treatment) after the final working or heat-treating step.

mill product

Any commercial product of a mill.

mill scale

The heavy oxide layer that forms during the hot fabrication or heat treatment of metals.

minnow bucket

See hone bucket.

model

An accurate representation showing size and form of a part.  Different types of models are used in different stages of the part development from preliminary design to final checking.  Such models include clay models, plastic models, wood models, etc.

modified flat hem

Modified flat hem is believed to create better reflection characteristics on the finished panel assembly. (See Figure M4)

modulus of elasticity, (e)

The ratio of stress to strain during elastic deformation when material is under uniaxial tension. (See Figure M5)

The measure of rigidity or stiffness of a metal; the ratio of stress, below the proportional limit, to the corresponding strain.  In terms of the stress-strain diagram, the modulus of elasticity is the slope of the stress-strain curve in the range of linear proportionality of stress to strain.  Also known as Young's modulus.  For materials that do not conform to Hooke's law throughout the elastic range, the slope of either the tangent to the stress-strain curve at the origin or at low stress, the secant drawn from the origin to any specified point on the stress-strain curve, or the chord connecting any two specific points on the stress-strain curve is usually taken to be the modulus of elasticity.  In these cases, the modulus is referred to as the tangent modulus, secant modulus, or chord modulus, respectively.

multiple die

A die used for producing two or more identical parts at one press stroke.

multiple-slide press

A press with individual slides, built into the main slide or connected to individual eccentrics on the main shaft, that can be adjusted to vary the length of stroke and the timing.  See also slide.

multi-tooth cutter

See roughing cutter.

m-value

See strain-rate sensitivity.