THE BLUE PRINT
  • Articles
    • Case Studies
    • Supply Solutions
    • Expert Consultants
    • Industrial Services
    • Safety
    • Compliance & Sustainability
    • Supplier Insights
    • Engineering
  • Webinars
    • Meet the Experts
  • Magazine
    • Subscribe
    • Contact Us
  • Articles
    • Case Studies
    • Supply Solutions
    • Expert Consultants
    • Industrial Services
    • Safety
    • Compliance & Sustainability
    • Supplier Insights
    • Engineering
  • Webinars
    • Meet the Experts
  • Magazine
    • Subscribe
    • Contact Us
Search

How to use flap disks safely and efficiently

July 11, 2023
By Walter Surface Technologies
 for the Blue Print
Flap disk

Working angle and pressure

  • Operate the flap disc at an angle between 2° and 15° for type 27 or 15° and 25° for type 29.
  • Do not exceed those angles to ensure an efficient and safe application.
  • Apply the optimal pressure by letting the rotational speed of the flap disc do the work.
  • Applying excessive pressure that bends the outer edge of the flap disc leads to premature wear and decreased tool life.
​​​​

​Proper operational speed

  • For optimal performance, move the flap disc along the surface slowly and steadily allowing the rotation of the flap disc to do the work.
  • Do not move the flap disc too quickly, nor aggressively back and forth. This will decrease its performance and provide a rougher surface finish.
  • Faster does not equal better when it comes to flap discs.​​
​​
Picture


​Proper trimming

Picture
Incorrect trimming can damage the flap disc. Some rules of thumb are:
  • Never trim at a 90°angle since this increases the risk of kickback.
  • Trim on secure sharp edges only.
  • Gently guide the backing of the flap disc towards the cutting edge.
  • Slightly angle your grinder between 15 and 25 degrees and, once the adhesive begins to appear, lower your angle, and stop trimming.
  • Unveil ¼” (6 mm) of new overhang at a time.
  • DO NOT trim the backing more than the recommended number of times as it will damage the structural integrity of the backing.
​​

Caution! To avoid for risk of accident!

  • Avoid simultaneous contact at several grinding points due to risk of kickback. The flap disc could stop rotating if stuck, which may result in breakage of the flap disc.
  • DO NOT use the flap disc inside of square tubing.
  • DO NOT hit the flap disc against a sharp edge.
  • Avoid intense impact on the flap disc’s backing.
  • DO NOT grind into narrow workpieces. The flap disc can be drawn in, which can lead to sudden wheel stop and wheel breakage.

​When using flap discs, always wear PPE, particularly, heavy-duty gloves, long sleeves, and eye protection, like safety glasses, goggles, or face shields. 

Proper mounting

Picture
(1) Backing Flange (2) Clamping Nut (3) Integrated Backing Flange (5) Backing Flange (6) AVOID: Clamping Nut Inserted Upside Down
​​
  • Situation 1: Needs a backing flange with a clamping nut. Note: The long face needs to sit on the disc (avoid situation 3).
  • Situation 2: Integrated backing flange with clamping nut. Note: In rare cases, the power tool includes this backing flange.
  • AVOID Situation 3: don’t forget to add the back flange because the backing pad of the flap disc can rub on the head of the power tool and lower performance. Note: The number 6 indicates a clamping nut inserted upside down which leads to excessive pressure around the hole, increasing risk of breakage. The long face should be in contact with the disc.
  • Situation 4: Needs a backing flange ONLY. 
​​

Extra safety tip

Take comfort and vibration into account when using flap discs, especially if used regularly and for long periods of time. Worker fatigue increases the risk of accidents and long-term exposure to vibration can lead to health issues down the road.
​
  • Avoid standard fiberglass flap discs as they don’t absorb vibration, but instead pass it on to the worker.
  • Nylon is a better alternative to fiberglass but still transfers some vibration to the worker. 
​​
​
Content originally from Walter Surface Technologies. Reused here with permission.
Vertical Divider
Want to see more supplier content? Click here.
Subscribe

​Got feedback?
 Email us at
[email protected]
Company Information
Fastenal.com
About Us
​
Accessibility
​
Blue Lane Freight
Careers
ESG
Investor Relations
Legal Information
Privacy Statement
Social Responsibility
Vehicles for Sale
Support
Contact Us
Customer Support
Find a Branch
​International Orders
​
Certification Library
Services & Solutions
​Website Feedback
Promotions & Publications
Help & Support
Marketing Information
Fastenal Branding
Fastenal Brands
​
Partnerships in Action
​
​Press Room
​NHL Partnership
​
RFK Racing Partnership
Supplier Partners
Associated Websites
Av-Tech Industries
BK5K
Cardinal Fastener
​Fastenal Brazil
​Fastenal Canada
Fastenal China
Fastenal Europe
Fastenal Mexico
Holo-Krome
​Innova Supply Chain Solutions 
Mansco
Spensall
Stay Connected
Stay In The Know
Sign up for the latest deals and our free magazine.
Sign Up
Got Feedback?
Email us!
WHERE INDUSTRY MEETS INNOVATION
Copyright © 2025 Fastenal Company. All Rights Reserved.
  • Articles
    • Case Studies
    • Supply Solutions
    • Expert Consultants
    • Industrial Services
    • Safety
    • Compliance & Sustainability
    • Supplier Insights
    • Engineering
  • Webinars
    • Meet the Experts
  • Magazine
    • Subscribe
    • Contact Us