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Course 726 - Introduction to Machine Guarding

Safety guides and audits to make your job as a safety professional easier

Machine Guard Construction

Builder-Designed Guards

Manufactured guard.
Manufactured guards are usually designed better.

Today many manufacturers or builders of single-purpose machines provide point-of-operation and power transmission safeguards as standard equipment. However, not all machines in use have built-in safeguards provided by the manufacturer.

Advantages of Builder-Designed Guards

Guards designed and installed by the builder offer two main advantages:

  • They usually conform to the design and function of the machine.
  • They can be designed to strengthen the machine in some way or to serve some additional functional purposes.

1. What is a major advantage of builder-made machine guards?

a. They are often the only practical solution
b. They can be built to fit unique situations
c. They help promote safety consciousness
d. They conform to the design and function of the machine

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User-Designed Guards

gsg photo - Manual feed
User-designed guards may not conform to requirements.

Advantages of User-Built Guards

User-built guards are sometimes necessary for a variety of reasons. They provide the following advantages:

  • Often, with older machinery, they are the only practical safeguarding solution.
  • They may be the only choice for mechanical power transmission apparatus in older plants, where machinery is not powered by individual motor drives.
  • They permit options for point-of-operation safeguards when skilled personnel design and make them.
  • They can be designed and built to fit unique and even changing situations.
  • They can be installed on individual dies and feeding mechanisms.
  • Design and installation of machine safeguards by plant personnel can help to promote safety consciousness in the workplace.

Disadvantages of User-Built Guards

User-built guards also have disadvantages:

  • User-built guards may not conform well to the configuration and function of the machine.
  • There is a risk that user-built guards may be poorly designed or built.

2. Which of the following is a disadvantage of user-built machine guards?

a. They must be built by skilled personnel
b. They may be poorly designed or built
c. They are often placed within older equipment
d. They cannot fit unique machine requirements

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Point-of-Operation Guards

Point of Operation Guard

Point-of-operation guards are designed to prevent workers from accidentally or intentionally inserting a finger, hand, foot, or any other body part into the operating machine.

Point-of-operation safeguarding is complicated by the number and complexity of machines and also by the different uses for individual machines. For these reasons, not all machine builders provide point-of-operation guards on their products.

In many cases a point-of-operation guard can only be made and installed by the user after a thorough hazard analysis of the work requirements. Poorly designed, built or installed guards may create a hazard rather than eliminate one.

To be effective they must safeguard the employee while allowing the work to continue with minimum disruption to the production process.

3. Which type of machine safeguards are designed to prevent workers from inserting a body part into the operating machine?

a. Presence-sensing
b. Automatic feed
c. Point of operation
d. Power distribution

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Mechanical Power Transmission Apparatus Guarding

Robots are used for replacing humans who were performing unsafe, hazardous, highly repetitive, and unpleasant tasks

A significant difference between power transmission guards and point-of-operation guards is that the former type needs no opening for feeding stock. The only openings necessary for power transmission guards are those for lubrication, adjustment, repair, and inspection. These openings should be provided with interlocked covers that cannot be removed except by using tools for service or adjustment.

To be effective, power transmission guards should cover all moving parts in such a manner that no part of the operator's body can come in contact with them.

4. To be effective, power transmission guards should cover all moving parts in such a manner that ______ cannot come in contact with them.

a. any part of the operator's body
b. fingers and hands
c. the head or hair
d. feet or legs

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Fixed Guard and Robot

Guard Material

Under many circumstances, metal is the best material for guards. Guard framework is usually made from structural shapes, pipe, bar, or rod stock.

Filler material generally is expanded or perforated or solid sheet metal or wire mesh. It may be feasible to use plastic or safety glass where visibility is required.

Guards made of wood generally are not recommended because of their flammability and lack of durability and strength. However, in areas where corrosive materials are present, wooden guards may be the better choice.

5. Which of the following may be the best material for machine safeguards if corrosive materials are present?

a. wood
b. pipes
c. metal bars
d. metal screens

Check your Work

Read the material in each section to find the correct answer to each quiz question. After answering all the questions, click on the "Check Quiz Answers" button to grade your quiz and see your score. You will receive a message if you forgot to answer one of the questions. After clicking the button, the questions you missed will be listed below. You can correct any missed questions and check your answers again.

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