In-Line Inspection Applications 381

In-Line Inspection Applications offers an in-depth look at the uses of in-line inspection, or error-proofing, in a production environment. Error-proofing uses individualized setups to inspect a part while it is still in production. Gage selection for in-line inspection depends on variables such as part type, production specifics, environment, and process control needs. Possible gaging options include limit or proximity switches, counters or timers, photoelectric or laser sensors, air gages, machine vision systems, and ultrasonic systems. In-line inspection is only feasible if it can be done with repeatability and accuracy.

Inspection of parts during production, instead of after it is complete, allows a company to prevent errors before they occur and reach customers. After taking the class, users should be able to describe the various methods for incorporating in-line inspection into an established production process.

  • Difficulty Advanced

  • Format Online

  • Number of Lessons 16

  • Language English


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Course Outline
  • The Purpose of In-line Inspection
  • Best Practices of Error-Proofing
  • In-line Inspection Equipment
  • Equipment in Use
  • Common Tools
  • Gage Selection
  • Gaging an Assembly
  • Part Type
  • Part Production
  • Production Environment
  • Process Control Needs
  • In-line Inspection
  • Machine Specific Inspection Processes
  • The Feasibility of In-line Inspection
  • In-Line Inspection Applications
  • In-Line Inspection Benefits
  • Describe the purpose of in-line inspection.
  • Describe a rabit.
  • Describe how inspection equipment is used during production.
  • Describe different equipment options available for in-line inspection applications.
  • Describe considerations necessary for successful in-line gage selection.
  • Describe considerations necessary for successful in-line gage selection.
  • Explain how part type affects in-line gage selection.
  • Describe how part production variables affect in-line gage selection.
  • Describe the production environment variables that restrict in-line gage selection.
  • Describe process control.
  • Explain how machining processes impact in-line inspection.
  • Explain how the feasibility of in-line inspection depends on the situation.
  • Describe the costs and benefits of in-line inspection.
Vocabulary Term


The difference between a measurement reading and the true value of that measurement. The less error present in the measurement, the more accurate the results.

air gage

A variable, non-contact pneumatic instrument that uses pressurized air to inspect parts. Air gages can measure features with tight tolerances.


The process of fitting components together into a larger or completed part. Assembly commonly uses in-line inspection.

control chart

An example of a tool used in statistical process control. A control chart plots out inspection results and detects any readings outside of a specified acceptable range.


The main device that processes information and carries out instructions. A controller is also known as a processor.


A device that counts, calculates, or keeps a record of the number of times something happens. Counters are also known as timers.


A point of reference from which measurements are taken. A datum can be a hole, line, or any three-dimensional shape.

dedicated gage

A gage that is specific to one task and situation. Dedicated gages cannot easily be retooled for other purposes.


The amount of mass within a specific volume. The density of an object can be inspected using an ultrasonic system.


The scientific study of equipment design, workspace arrangement, and the environment to increase worker comfort, safety, and productivity. Ergonomics can be applied to any workplace.


The practice of installing processes that prevent defect rather than looking for defects after the fact. Error-proofing is also known as in-line inspection.


A device used to join two or more parts. Common fasteners include screws and bolts.

flexible gage

A gage that can be repurposed for a wide variety of tasks and situations. Flexible gages are needed when more than one type of part is produced on one line.


The physical inspection of part features using a device with an established standard size. Gaging in in-line inspection means continuously checking parts and processes for error.


A machine that uses an abrasive to machine a workpiece surface and achieve highly accurate measurements. Grinders commonly use abrasive grains bonded into a wheel shape.

in-line gaging

The inspection of a part that occurs directly after a part has been machined. In-line gaging is a form of in-line inspection.

in-line inspection

The practice of installing processes that prevent defect rather than looking for defects after they have occurred. In-line inspection is also known as error-proofing.

inner diameter

ID. The diameter measurement of a hole's interior surface. An inner diameter measurement extends the entire length of the hole.

in-process gaging

The inspection of a part that occurs while a part is being machined. In-process gaging is a form of in-line inspection.


A safeguarding device that causes a machine to stop when it is out of position. Limit switches can be used as interlocks.

laser sensor

A type of photoelectric sensor that uses a laser beam to inspect objects without physical contact. Laser sensors can detect small parts from a long distance.


A machine tool that holds and supports a cylindrical workpiece at one or both ends and rotates it while a single-point cutting tool removes material. Turning is a common operation performed on the lathe.

limit switch

A type of mechanical sensor that requires physical contact to detect the presence or absence of an object. Limit switches have a variety of actuators that come into contact with an object.

machine tools

A power-driven machine that uses a cutting tool to remove metal from a workpiece. Machine tools can sometimes require specialized gaging equipment.

machine vision system

An automatic identification system that uses computer processing equipment to recognize and identify materials based on images scanned by a camera or cameras. Machine vision systems analyze the pixels of a photo to locate defective parts.


The process of removing metal by producing chips through the use of cutting tools. Machining commonly uses in-line inspection.

measurement head

In-line inspection device used to determine quality control variables during machining. A measurement head is used as a dedicated gage for grinders during in-process gaging.


A machine that uses a rotating multi-point tool to remove metal from the surface of a workpiece. Mills often generate flat surfaces.

noncontact methods

A type of inspection that does not require the measuring instrument to contact the part surface. Noncontact methods allow for the inspection of soft, fragile materials and hot or hazardous parts.

outer diameter

OD. The diameter measurement of a cylindrical object's exterior surface. The measurement of the outer diameter extends the entire length of the cylinder.

photoelectric sensor

A type of sensor that detects the presence of an object through the use of a beam of light. Photoelectric sensors use no physical contact with the object being inspected.


The smallest piece of information in an image. When joined together, pixels form a cohesive image.


Creating power by the motion and control of gas under pressure. An air gage measures using pneumatics.


In-line inspection device used to determine quality control variables during machining. A probe is used as a dedicated gage for lathes and mills during in-process gaging.

process control

A method of checking product performance and batch consistency by regularly measuring and regulating processes that yield a product. Process control involves collecting and analyzing data to help reduce error.

production line

A manufacturing system in which materials are passed through successive processes in order to make a final product. Production lines utilizing in-line inspection can correct for errors before they affect productivity and increase costs.

proximity switch

A device that uses an electromagnetic field to sense the presence of an object. Proximity switches do not physically contact the object being detected.


A defective part used to check the accuracy and repeatability of an in-line inspection system. A rabit should be detected by a system 100 percent of the time.


The ability to deliver accurate and dependable results over a long period of time. In-line inspection requires repeatability to be successful.


Disposed unusable material. Scrapping defective parts incurs a cost that negatively impacts yield numbers.

statistical process control

SPC. The use of statistics and control charts to measure key quality characteristics and control how the related process behaves. With SPC, operators typically track the variation of part measurements over time.


Raw material used to make manufactured parts. Stock is available in standard shapes such as long bars, plates, or sheets.

surface finish

The degree of roughness and variation on the surface of a part after it has been manufactured. Due to irregularities created when machining a part, surface finish cannot be perfectly smooth.


A long, spiral ridge around the exterior or interior of a cylindrically shaped object. Threads are used to fasten or provide motion.


A device that counts, calculates, or keeps a record of the number of times something happens. Timers are also known as counters.


The total amount a specific dimension is permitted to vary. The object will still meet specifications if it remains within its tolerance.


A force that produces rotation. The torque of a cutting tool can be monitored using in-line inspection.

ultrasonic system

A type of sensor that uses sound or radio waves to detect an object. Ultrasonic sensors have the ability to detect liquids, clear objects, or irregularly shaped objects.


An undulation or vibration of a form of energy. Waves include sound and radio waves.