Surface Finishing Composites 190

Understanding how to finish the surface of a composite part helps an operator create parts that meet the demands of the customer. This class will teach you about surface finishing operations for composite parts.

  • Difficulty Beginner

  • Format Online

  • Number of Lessons 14

  • Language English


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Course Outline
  • Objectives
  • Surface Finishing Composite Parts
  • Manual Material Removal
  • Automated Material Removal
  • Polishing
  • Sanding
  • Cleaning
  • Surface Preparation
  • Priming
  • Painting
  • Plating
  • Inlaying, Hot Stamping, and Fill and Wipe
  • Other Decorative Processes
  • Summary
  • Describe surface finishing of composite parts.
  • Describe manual material removal.
  • Describe bulk material removal.
  • Describe polishing.
  • Describe sanding.
  • Explain how composite parts are cleaned.
  • Describe the importance of surface preparation.
  • Describe priming.
  • Describe painting.
  • Describe plating.
  • Distinguish between inlaying, hot stamping, and fill and wipe.
  • Identify other decorative processes.
Vocabulary Term

abrasive media

The materials used to impact and remove unwanted portions of composite parts during abrasive blasting. The media must be hard enough to remove the material, but not so hard that it damages the parts.

activator bath

A stage in the plating process that makes the surface of composite parts electrically attractive to the metals in later baths.

air spraying

A basic means of painting involving a spray gun. During air spraying, pressurized air atomizes the paint as it is released from the gun.


The break up of a liquid into small particles to produce a fine mist. Paint guns use compressed air to atomize paint for spraying.

color matching

The process of ensuring that painted surfaces achieve maximum similarity in hue and intensity. Color matching is vital when composite parts are placed next to metal parts.

cryogenic tumbling

A two part material removal process that first involves flash freezing parts using liquid nitrogen or similar gases, and then tumbling or vibrating the parts. Freezing parts makes them more brittle and allows material removal with little or no abrasives.


The process of removing unwanted material leftover from injection molding. Most degating is done manually either by hand or with simple hand tools.

diffuse reflection

Light rays that are reflected from a surface and broken up and scattered into different directions.

dry abrasion

The process of uniformly sanding a surface with an abrasive element, such as sandpaper. Dry abrasive methods do not use coolant.


A method of painting during which parts are electrically charged and then dipped into a vat of paint until they are fully covered. E-coating is typically used to prime parts.

electroless bath

A step in the plating process where parts are dipped in a metallic solution. Metal in the bath bonds to parts because previous baths have made the parts electrically conductive.

electroless plating

A decorative process that covers parts in a dull, metallic finish. Electroless plating can be a finishing process, but is often done in preparation for electrolytic plating.

electrolytic plating

A decorative process that covers parts in shiny chrome or copper finish. Electrolytic plating uses current to draw positively charged metals to negatively charged electroless plated parts.


The use of a chemical solution to selectively remove surface material. Etching is a part of the plating process.

fill and wipe

A decorative process that involves filling indentations in parts with paint. An operator then wipes the surrounding surface area clean, leaving paint only in the indents.


To alter the texture or appearance of a part. Some form of finishing is done on most composite parts.


The overflow of excess composite material that can leak out during the compression process.

flow coating

A method of painting where multiple streams of paint are dripped over parts as they are rotated. The runoff paint is captured and reused.


The path by which composite material travels from a runner system to the part mold in injection molding. After the part is complete, material in the gate remains attached to the part and must be removed.

high volume/low pressure spraying

A method of painting that uses less than 10 psi (70 kPa) of pressure in the spray gun. This results in a more controllable spray.

hot stamping

A decorative process during which heated dies transfer ink from a foil film into the surface of a part.


A decorative process during which a material of contrasting color or colors is inserted into a depression on the surface of a part.

media blasting

The process of removing unwanted material with an air blast that throws abrasive particles against the surface of the parts as they are cycled on a conveyor.

pad printing

A decorative process that uses a silicone rubber pad to transfer paint or ink from an etched image to the surface of a part. Pad printing can be done on a variety of surfaces and angles.


A decorative process that covers parts with a metallic coating. Plating is a detailed, multistep process, but results in a long lasting, durable coating.


An abrasive finishing process used to improve the surface of a part. Polishing results in a smooth, shiny surface.


To apply a coating typically used to improve adhesion. Epoxies are often used as primers.


A gentle grinding process that uses a fine grain abrasive to remove small amounts of surface material.

silk screening

A decorative process that uses a printed image on a finely woven screen. Ink or paint is then pressed through the porous screen and onto the surface of a part.

surface finishing

Any post fabrication process done to improve the surface texture or appearance of a part. Most composite parts require some form of surface finishing.


Manually removing flash or other unwanted material with a blade. Trimming requires skill and care from the operator.


A material removal process whereby parts are placed in a hopper and tumbled against themselves and possibly a light abrasive media. Traditional tumbling is often ineffective for composite parts due to their physical properties.

vacuum metalizing

A decorative process that places composite parts in a chamber along with small amounts of a metal. The metal is vaporized within the vacuum, and spreads over the surface of the composite parts.