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The shape of the disc pad of the lamellar disc and its effect on the grinding method
One of the categories of grinding tools intended for angle grinders is lamellar discs. They are also called lamellar discs, fan discs, lamellar discs with a convex center, etc. The main component is the sanding belts, from which the slats are cut and placed in a fan shape around the circumference of the disc. These belts belong to the group " coated abrasives". abrasives ) – that is, the abrasive grain is applied and then connected to the underlying fabric.
fig. 1 Abrasive belts for the production of lamellar discs
The area of use (type of machined material) mainly depends on the type of abrasive grain (most often corundum, zirconium corundum or ceramic grain), the grinding result mainly on the grit of the abrasive (most often P40 – coarse to P120 – fine grit).
However, there is one more thing worth noting.
The shape of the plate mat
Abrasive discs with lamellas arranged in a fan are produced with a disc pad of mainly flat (T27) or conical (T29) shape. What is the difference in the purpose of their use?
The disc pad is the carrier of the sanding plates. These components are connected to each other with a special glue based on epoxy resin.
fig. 2 Flat and conical plate washer
fig. 3 Flat lamellar disc
Flat lamellar disc
The basis is a flat disc pad (type 27): the contact surface is perpendicular to the angle grinder shaft.
Flat lamellar discs are most effective at an angle of 0-15°. Full use of the contact surface is only at 0° tilt. However, such a position of the angle grinder is only possible when machining smaller surfaces or the edges of large surfaces.
On flat surfaces, you can effectively sand large unevenness with such a lamella disc. The small contact area of the lamellar disc allows you to focus precisely on the critical spot.
Lamella discs on a flat base are also suitable for unifying surfaces and very good for finishing work. They are primarily used to remove larger irregularities and are the best choice for unifying the machined surface on the faces and outer corners of metal workpieces.
fig. 4 Small contact area of the lamellar disc with the workpiece
fig. 5 Conical lamellar disc
Conical lamellar disc
The base is a conical plate washer (T29): the contact surface of the lamellar disc is inclined. The recommended angle for machining is 15˚ - 25˚. An angle grinder tilted in this way will make it possible to make full use of the large contact area of the lamella disc with the workpiece - it is therefore a very good solution for sanding wood products as well.
Tapered wheel is the most popular for metalworking. It rests on the workpiece with a larger surface, the inclined angle of the grinder creates a leverage effect, and thus more pressure. This makes work significantly more efficient and easier and is an excellent helper in removing corrosion and dirt from large areas.
Adhering to the recommended angle range is not difficult at all, because the angle grinder is in a natural position in the hands.
fig. 6 Large contact area of the lamellar disc with the workpiece
Final summary and comparison of T27 and T29
- Flat shape
- Targeted sanding with a small area
- Angle during machining: 0˚ - 15˚
- For unifying surfaces on surfaces and external corners
- Conical shape
- Grinding with a large area
- Angle during machining: 15˚ - 25˚
- More aggressive grinding, better contact when removing surface irregularities, corrosion and paint residues
The common feature of flat and conical lamellar discs is the same production technology and the same components, so their price should be the same. When choosing between T27 and T29, only one thing is important: do you want to grind with a large or small contact area? For better memorization, we use the name Area or Canta , which characterize a large or small area. True, there is also Punta , but more on that next time.
Sources:
HERMAN internal technical and training materials
https://www.empireabrasives.com/blog/t27-vs-t29-flap-disc-differences/
https://handymansworld.net/t27-vs-t29-flap-disc/
Ing. Herman Nagypál
I graduated from a military school. I learned to work with tools and equipment as a child with my father on the construction of our family house. I test each of our new products personally - with my own hands in my well-equipped workshop. In my spare time, I study trends in the field and like to try competitive products. Some of them make me laugh, and some of them make me wonder (that someone got caught and bought it), but some are really good. Almost like ours 😊.
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