Manufacturing Defect Examples | Manufacturing And Design Defects

Manufacturing defect examples may be used to educate employees on potential defects. A manufacturing defect is a defect in a manufactured item that occurred during the manufacturing process. Manufacturing defects may be the result of design flaws or poor quality control.

Overview of Manufacturing Defect Examples:

Manufacturing defects happen to the best of us. It is a lot easier to list out the causes of manufacturing defects than it is to prevent them entirely. There are many layers and processes that go into making a product, and even with the best of intentions, a defect can always slip through. While not all manufacturing defects are created equal, there are some general categories that they fall into.

Manufacturing defects are those that occur during the manufacturing process. This can be due to a variety of factors, from human error to faulty machinery. In many cases, these defects can lead to severe injuries and even death for a consumer. However, there are ways to identify a defect in your own products before they cause an injury or other problems.

The National Institute of Occupational Safety and Health (NIOSH) defines a “manufacturing defect” as any problem with a product that occurred before it left the control of the manufacturer. Defects can result from many different types of problems. Some defects are the result of human error, such as a worker accidentally dropping small parts or screws into the machine during assembly. Other defects may occur because of poor training, such as an operator who doesn’t know how to properly adjust the settings on a machine.

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Types of manufacturing defects:

1. Design Defects – which occur when a product is designed in such a way that it is dangerous even when used as intended.
2. Manufacturing Defects- which occurs due to an error in the production process, causing the product to be defective or unsafe even when used as intended.
3. Marketing Defects– which occurs during the marketing process and involves a failure in the instructions provided by the manufacturer on how to use or install

Major manufacturing processes and its defects

The major materials used for engineering activities are grouped into four classes, namely,

  1. Metals and Alloys,
  2. Ceramics,
  3. Polymers and
  4. Composites.

Each of these materials has a distinct property profile.

Pure metals find limited application, while metals and alloys (ferrous and Non ferrous) are the most widely used engineering materials. Materials are subjected to many manufacturing processes to produce not only the desired shape but also to ensure the design – stipulated physical and mechanical properties and dimensional tolerances. Further, components are provided with necessary surface protection from corrosion and erosion. However, all manufacturing operations and service environments induce various types of defects in engineering components, which need to be detected and evaluated.

1. Casting:

  • Sand casting,
  • Die casting,
  • Permanent mold casting,
  • Investment Casting and
  • Continuous casting

Casting Defects Encountered during Manufacturing and Service

  • Inclusions,

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  • Segregations,
  • Gas pockets,

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  • Internal shrinkage,
  • Surface crack,

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  • Pipes,
  • Gas porosity,

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  • Hot tears,

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  • Cold shuts, and

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  • Cavities

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2. Welding:

  • Gas welding,
  • Resistance welding,
  • Arc welding,
  • Friction welding,
  • Brazing,
  • Soldering and
  • Diffusion bonding

Welding Defects Encountered during Manufacturing and Service

  • Lack of fusion,

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  • Incomplete penetration,
  • Cracks,

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  • Slag inclusion,
  • Gas porosity,

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  • Crack in parent metal,
  • Root undercutting

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3. Forming:

  • Forging,
  • Rolling,
  • Wire drawing,
  • Deep drawing,
  • Bending,
  • Extrusion

Forming Defects Encountered during Manufacturing and Service

  • Inclusion,

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  • Segregation,
  • Pipes,
  • Seams,

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  • Laps,
  • Bursts,

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  • Cracks,
  • Tears,

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  • Lamination,

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  • Flakes,
  • Rolled-in scale,
  • Roll mark,
  • Die-mark,
  • Thermal crack

4. Machining:

  • Cutting,
  • Drilling,
  • Turning and
  • Milling

Machining Defects Encountered during Manufacturing and Service

  • Cracks,

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  • Nicks,
  • Scratches and ridges,
  • Tears and laps,
  • Hardness alteration,
  • Residual stress distribution,
  • Deformed debris,
  • Grain size change,
  • Inter-granular corrosion,
  • Embrittlement cracks

5. Powder metallurgy:

  • Compressing of metal powder into solid mass by application of pressure and heat

Powder Metallurgy Defects Encountered during Manufacturing and Service

  • Porosity,
  • Cracks,
  • Inclusion,
  • Variation in density distribution

6. Heat treatment:

  • Specific to alloys to impart desired microstructure, hardness, strength and stiffness

Heat treatment Defects Encountered during Manufacturing and Service

  • Cracks,
  • Segregation,
  • Grain size changes

7. Surface protection:

Surface protection of components is provided by organic, inorganic and metallic coating:

  • Organic coating: Paints and lubricants
  • Inorganic coating: Phosphating and chromating
  • Metallic coating: Electroplating, coating by diffusion e.g. galvanizing, aluminizing, metalizing by a spray of partially melted material

Surface protection Defects Encountered during Manufacturing and Service

  • Dents,
  • Scratches,
  • Change in thickness of coating,
  • Insufficient protection of surface, and Erosion of protective

References

  1. Casting Defects
  2. Welding Defects
  3. Heat Treatment Defects