Rapid Prototyping Glossary R | Attwood Product Development

Ra

The arithmetic average surface roughness parameter commonly used on engineering drawings.

Radial hole

A hole perpendicular to the axis of a turned part, often made with live tooling.

Rapid injection moulding

Injection moulding performed with faster-turn, lower-cost tooling so prototype and bridge-volume parts can be produced before committing to full production tooling.

Rapid liquid printing

RLP; an additive process that rapidly dispenses and cures liquid material, often with robotic multi-axis motion for larger-format parts.

Rapid tooling

The accelerated creation of tooling using CNC machining, additive methods or simplified tool design.

Rapid traverse

A non-cutting machine movement at high speed used to position the tool between machining moves.

Reaction injection moulding

RIM; a process in which reactive liquid components mix and cure in the mould.

Reamer

A multi-edge tool used to size and finish an existing hole with improved accuracy and surface condition.

Reaming

The finishing operation of bringing a pre-drilled hole to a more precise final diameter using a reamer.

Recoater

The mechanism that spreads a fresh powder layer in a powder-bed machine.

Recoating blade

The blade or roller used to distribute a new powder layer across the build area.

Reference dimension

A dimension shown for information only and not usually used for acceptance.

Registration

Accurate alignment between successive layers, colours, operations or assembled components.

Reinforced reaction injection moulding

RRIM; a reaction injection moulding variant that uses reinforcement to improve stiffness, strength and impact performance.

Release agent

A material applied to a tool or mould to help a part separate cleanly.

Repeatability

The ability of a process or machine to produce the same result repeatedly under the same conditions.

Residence time

The length of time the polymer remains in the heated barrel, manifold or nozzle before injection. Excess residence time can cause degradation, colour shift or material property loss.

Resin infiltration

Introducing a secondary resin into a porous or powder-derived part to improve strength or density.

Resin transfer moulding

RTM; a composite process in which resin is injected into a dry fibre preform inside a closed mould.

Resin viscosity

The flow resistance of a liquid resin, affecting filling, jetting and impregnation.

Resolution

The minimum detail a process can reproduce or the fineness of the machine step or pixel size.

Rest machining

A follow-up toolpath that removes residual material left by a larger cutter in corners, fillets or tight areas.

Retaining feature

A geometry such as a clip, barb or undercut used to hold a mating component in place.

Revolutions per minute

RPM; the rotational speed of a spindle, tool or workholding element measured as complete turns per minute.

Rib

A thin reinforcing wall used to stiffen a part without making the whole section thick.

Rib-to-wall ratio

The relationship between rib thickness and nominal wall thickness, important for mouldability and sink control.

Rigid tapping

A tapping method in which spindle rotation and axis feed are synchronised so threads are cut without a floating holder.

RIM

Abbreviation for reaction injection moulding.

RIM press

A dedicated reaction injection moulding machine that meters, mixes and injects reactive liquids into the mould.

Ring gate

A circular gate used to feed tubular or symmetrical moulded parts evenly.

RLP

Abbreviation for rapid liquid printing.

Roads

Individual deposited beads of extruded material in filament printing.

Robot polishing

Automated polishing using programmed robotic motion for consistent finish.

Rockwell hardness

A metal hardness scale based on indentation depth under a specified load.

Rotary table

A rotating fixture or machine axis used to present different faces of a part to a tool.

Rotational moulding

Also called rotomoulding; a hollow-part process in which a heated mould rotates while polymer coats the inside surface and fuses.

Roto casting

An alternative name sometimes used for centrifugal casting, emphasising the rotational filling method.

Router

A CNC machine commonly used for softer materials, composites, boards and sheet goods.

RPM

Revolutions per minute; a standard speed unit used when specifying spindle or rotary tool speed in machining.

RRIM

Reinforced reaction injection moulding; a RIM variant that incorporates reinforcement to improve strength and impact performance.

RTM

Abbreviation for resin transfer moulding.

Runner balance

The degree to which melt reaches multiple cavities under equal flow and pressure conditions. Balanced runners are essential in family and multi-cavity moulds to achieve consistent fill and weight.

Runout

Variation in the rotation of a feature relative to its datum axis.