Contract assembly or contract manufacturing is the process of using a third-party manufacturing company to manufacture a product. A contract assembler does not own the product design or rights. The design of the product and all details of its production can be dictated to the contract manufacture by the product owner although the product owner may defer certain decisions to the contract manufacture because of their level of experience.

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2D Drawing

Two-dimensional drawings show the product or part in a series of views. Each view has dimensions that show the measurements of the features. In addition, the dimensions also commonly include tolerances (see glossary). Two-dimensional drawings are usually made by an engineer and are commonly drawn by using a program called AutoCAD.

3D Solid Model File

Three-dimensional solid model files are 3D representations of a part in a computer program. Within the computer program this part can be rotated to see different features and split to see the inside. In addition, the software can make calculations to determine the amount of material that is required to make the part. Also, 3D solid model files can be exported to machines that will make prototypes (see SLA) and make production tooling. Any custom made plastic parts require 3D solid model files to be produced before tooling can be made. 3D solid model files are commonly made with software such as SolidWorks and Pro/ENGINEER.

Assembly Instructions

When a custom product is to be assembled, the manufacturer and workers need assembly instructions to teach them the proper method of assembly. These instructions break down the assembly process into a series of steps and give specific instructions. It is common for parts of these assembly instructions with pictures to be posted at the individual workstations of the assembly staff.

Critical Dimension

Some parts are very complex and the only way to communicate every dimension is via a 3D solid model file (see glossary). When an individual desires to measure the part to see if it is correct, it is unwieldy to have to measure every dimension. For this reason, part designers commonly create special 2D drawings (see glossary) that illustrate critical dimensions of the part. These critical dimensions are the most important dimensions and are meant to be checked more often than other dimensions. Also see "From Fit and Function."

Design Sketch

A design sketch is either a computer or hand drawn sketch meant to illustrate the look or basic function of a product.

Engineering Drawings

Engineering drawings are drawings that are designed to communicate important information about the subject of the drawings such as dimensions, tolerances, material. Engineering drawings are drawn and information is provided using industry wide standards and conventions.

Fixture

In manufacturing, a fixture is a term used to describe any custom apparatus used to help standardize a process or make a manual task easier.

Industrial Designer

An industrial designer is an individual who designs the look and usability of a product. Industrial designers are commonly used in the early phase of the product development process to design the concept of the product. These concepts are then usually transitioned over to an engineer to create the engineering drawings (see glossary)

Injection Molding

Injection molding is the process of making custom plastic parts by injecting molten plastic material into a metal mold. This mold contains a carving or imprint of the desired part. After the molten plastic is injected into the mold, the mold is cooled, the mold is split open and the solidified plastic part is ejected. The process is then repeated. Injection molding is a widely used process for making high volume custom plastic parts. (for more info, see cavitation)

Machining

Machining is the process of carving a piece of raw material into a desired shape. It is one of the most precise manufacturing methods but also one of the most expensive for mass production.

Prototype Tooling/Mold

In some cases, it is preferable to make a low-cost mold that will quickly wear out. This mold is called a prototype mold. The reasons for its production could be to test a design before full production or to produce a small number of accurate production parts. Prototype molds are made with low-grade material, are faster to fabricate and can usually produce 500-1000 production parts.

Rotational Molding (Rotomolding)

Rotational molding is a method commonly used to made large hollow plastic parts. To produce a part, powdered plastic resin is placed in a metal mold. This mold is then heated causing the plastic to melt. The mold is then slowly rotated around 2 perpendicular axes spreading the plastic around the inside of the mold. As the plastic cools and hardens, the part takes shape. After the part is cool, the mold is opened to reveal it. This process is rather slow compared with other manufacturing processes. Rotomolding is an efficient way to make large, low-volume, hollow parts.

Screen Printing

Screen-printing is a method of painting a custom graphic on a surface. Paint is pushed over a custom metal screen that acts as a stencil and paints a repeatable graphic onto parts.

Secondary Operation

A secondary operation is a generic term that is defined by any follow-up operation that must be completed after the main production process is complete. For example if a part is molded and a hole must be drilled into the molded part, the drilling would be a secondary operation.

Stamping

Stamping is a generic term that is used to describe all forms sheet metal work. These processes include stamping, bending forming and coining. Stamping uses large machinery to manipulate the shape of pieces of sheet metal. It is an efficient manufacturing method commonly used to make production parts.

Tolerance

While part dimensions are typically only one number, it is impossible to produce anything to an exact dimension. Every manufactured part is subject to variation. How much variation is allowed is defined by the measurement's tolerance. The tolerance is determined by the designer of the part. A "high" or "tight" tolerance is more difficult to achieve than a "low " or "loose" tolerance. Some manufacturing processes can deliver tighter tolerances than others.