ACMSO ACMS flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Surface feet per minute

Cutting speed expressed as the linear speed of the workpiece or tool surface past the cutting edge, in feet per minute; converted to spindle RPM using part diameter.

Climb versus conventional milling

Climb milling feeds the cutter with rotation, thinning chips and improving finish on rigid machines; conventional milling feeds against rotation and is preferred on older machines with backlash.

Bend allowance

The arc length of the neutral axis through a sheet metal bend, calculated from bend angle, inside radius, and K-factor, and used to calculate flat pattern length.

Additive versus subtractive

Additive processes build parts layer by layer from a digital model; subtractive processes cut material away from a solid blank to reach final geometry.

Five-axis machining

A machining configuration with three linear and two rotary axes, enabling complex contoured parts and undercut features to be cut in a single setup.

Die casting tolerance

A high-volume casting process using reusable steel dies that produces the tightest as-cast dimensional tolerances and smoothest surfaces among common casting methods.

Design for manufacturability

A design approach that simplifies geometry, reduces part count, and aligns tolerances with proven process capability to lower cost and defect risk.

Datum reference frame

Three mutually perpendicular planes established by primary, secondary, and tertiary datums that constrain all six degrees of freedom for inspection and tolerance measurement.

Maximum material condition

A modifier meaning the feature contains the maximum allowable material; it grants bonus tolerance as the actual feature departs toward least material condition.

Position tolerance

A GD&T control that defines a cylindrical or spherical zone within which the axis or center plane of a feature must lie relative to datums.

Minimum bend radius

The smallest inside radius a sheet can be bent without cracking, commonly about one material thickness for mild steel and larger for high-strength alloys.

Thread class of fit

A designation such as 2B or 3A that specifies the allowance and tolerance range between internal and external threads, controlling looseness or tightness of assembly.

Process capability index Cpk

A statistic comparing the distance from the process mean to the nearest specification limit against three standard deviations, measuring actual centered capability.

Control chart purpose

A chart with statistically derived limits that separates common-cause variation from special-cause variation so that only assignable causes trigger corrective action.

Gauge R&R

A measurement systems study quantifying repeatability (equipment variation) and reproducibility (appraiser variation) as a percentage of total tolerance or process variation.

First article inspection

A documented verification of the first production part against every drawing and specification requirement, performed before authorizing full production runs.

AQL sampling

An acceptance sampling method that uses lot size and inspection level to select a sample size and acceptance number based on an acceptable quality level.

Go/no-go gauge

An attribute inspection tool with two members: the go member must pass and the no-go member must not, verifying that a feature lies within limits.

Worst-case tolerance stack

A stack-up method that arithmetically sums all component tolerances, guaranteeing assembly even when every dimension is at its extreme limit.

Root-sum-square stack-up

A statistical tolerance stack that combines independent component tolerances as the square root of the sum of squares, yielding a tighter and more realistic total.

Thermal expansion formula

The change in length of a part equals the coefficient of thermal expansion times original length times temperature change; used to correct measurements and fits.

Clearance versus interference fit

In a clearance fit the hole is always larger than the shaft, allowing motion; in an interference fit the shaft is larger, requiring force or heat to assemble.

Surface roughness Ra

The arithmetic average deviation of a measured surface profile from its mean line, reported in microinches or micrometers and used to specify finish requirements.

Austenitic stainless steel

A 300-series stainless family that is generally non-magnetic and strengthened by cold work rather than by heat treatment.

Economic order quantity

The order quantity that minimizes the sum of ordering and inventory holding costs, calculated from annual demand, order cost, and holding cost per unit.

Takt time

Available production time divided by customer demand rate, defining the pace at which a process must complete one unit to meet demand.

Little's Law

A queueing relationship stating that work-in-process equals throughput rate multiplied by average flow time through the system.

Critical path

The longest sequence of dependent tasks through a project network; its duration sets the minimum possible project completion time.

Finite capacity scheduling

Scheduling that assigns work to resources only up to their available hours, preventing overload and producing a realistic, executable production plan.

Overall equipment effectiveness

A production metric computed as availability multiplied by performance multiplied by quality, expressed as a percentage of ideal operating time.

Lockout tagout

A required safety procedure that isolates and de-energizes equipment during servicing so that stored or unexpected energy cannot injure workers.

Hierarchy of controls

A ranked approach to hazard reduction: elimination, substitution, engineering controls, administrative controls, and finally personal protective equipment.