Choosing the right Fiber Disc for your grinding application

An angle grinder is a useful tool for any shop! You can use bonded grinding wheels, cut-off wheels, overlap discs or standard fiber discs all on this same tool for many different applications in metalworking, woodworking and stone or tile.

Abrasive Resource just lowered their prices on resin fiber grinding discs, so we thought it would be a good time to review all of the different applications where a fiber disc would be effective:

Aluminum Oxide: A general purpose abrasive used for metal or wood. Removes small welds and imperfections along with light stock removal, blending and finishing. Wood applications include log furniture and homes. These AO discs are also used in light-duty metal applications on low alloy steel or when loading is a problem, such as painted surfaces or aluminum. 

Zirconia: The workhorse of the fiber disc world. Zirconia refractures for longer life when used in high pressure applications like stock removal on Chrome and chrome-nickel steel or high-alloy steel. Used for applications that include blending, deburring and weld removal. Generally lasts twice as long as an aluminum oxide disc when used in the proper application. 

Ceramic: A premium abrasive for high heat generating applications such as stainless as it resists glazing and provides long life. The choice of metalworking professionals due to self-sharpening characteristics that provide high stock removal rates. Features cool cutting technology for reducing heat and increasing performance. Ideal for grinding and blending welds. 

Silicon Carbide: Excellent on titanium, fiberglass, plastics, and stone, tile and masonry products. Sharp silicon carbide abrasive grain quickly “bites” to remove any coatings such as adhesives, paint, acrylics, mastics, etc. Aggressive cutting action provides a clean, smooth finish on concrete, marble, granite, and other stonework. 

To purchase any of these discs at the new lower price, please visit the Abrasive Resource fiber disc home page on our website to find the discs best for you!

What are Non-Woven Abrasives?

 
Traditional coated abrasives are a cloth or paper backing that has abrasive grain “coated” or applied to one side. But a non-woven abrasive is composed of a synthetic substrate onto which a slurry of resins and abrasive grain are deposited. Non-woven abrasives are divided into two categories—they are either scrim backed, which is also known as surface conditioning products or non-scrim backed, which are the surface finishing, or open web products.

Surface Conditioning: Scrim backed materials are manufactured by needling synthetic fibers into a woven base of monofilament threads known as the scrim. It looks a little bit like burlap. This forms a fuzzy textured substrate on one side onto which a slurry of resins and abrasive grit are deposited. Since the material is only coated on one side of the material, it must be used flat with the grit side down—just like a coated abrasive, so it used primarily for belts or discs. These products are well suited for nearly all metals and used for gasket, paint, rust, scale and oxidation removal as well as light deburring, weld blending and for satin or decorative finishes.

Surface Finishing: Non-scrim, open web material is identified by the absence of the woven base or scrim for strength. It is more homogenous than scrim backed material with the resin and abrasive grain evenly distributed throughout. The nylon or polyester fibers are needled together to form an open, spongy mesh, which is then dipped into the resin and abrasive grit mixture. The result is a lightweight and flexible abrasive material that is less aggressive, more non-loading and more forgiving than the scrim backed material. It is very flexible and long wearing. The finishing material is then converted into discs, hand pads, rolls and other abrasive specialties.

Check out both the Surface Conditioning and Surface Finishing abrasives in the Non-woven Abrasives section on our website.

What do those arrows mean on the back of my sanding belt?

When sanding with a belt sander, you always want to make sure your belt is
oriented properly. Some sanding belts do have a preferred direction, and they
have been manufactured to consider the arrow on the inside. These arrows,
however, are only important to pay attention to when your belts have an
overlapped joint and there is a “bump” to be concerned with. In that case, you
will want the arrows on the inside of the belt to follow the same direction that
the belt is running on the sander. Most belts made in the United States---and all
of the sanding belts we convert at abrasiveresource.com -- are now manufactured with a high strength tape butt joint, and belts made with these butt joints can be
run in either direction . . . so it's OK to ignore the arrows. The tape spliced joints are bi-directional.
Bi-directional belts can be installed either way. The only adjustment you’ll probably have to make is “tracking” to keep the belt centered on the rollers. Hold the sander up, turn it on, and see if the belt either rubs against the housing or starts working its way off the rollers. With the trigger on, adjust the tracking knob until the belt is centered on the rollers. You may have to make a slight adjustment when the sander is on your work piece. If your sander has automatic tracking, you won’t need to be concerned with manually adjusting the tracking.

Basic Sanders

The basic styles of portable sanders haven’t changed very much over the years. We have some old advertising posters from the Rockwell Manufacturing company in 1964 matted, framed and hanging in our lobby here at Abrasive Resource and they, quite frankly, look a lot like sanders you can purchase today… although they do look much heavier! Sanding is a chore—there’s no way around it. But today’s new models can make it easier:

Basic Portable Sanders:

Belt Sanders- Portable belt sanders are made for fast removal of stock. They will quickly smooth down and level a surface, remove paint or glue lines. They are available in several sizes, but the most popular handle belts in a 3" x 18", 3" x 21", 3" x 24" or 4" x 24" size. 

Random Orbit Sanders- Once the surface has been leveled with a belt sander, the next sander to use may be a random orbit disc sander. These sanders use an oscillating action that removes swirl marks. Random–orbit sanders may be palm sanders or have a grip design and are available in either a pressure sensitive adhesive (PSA disc) design or a hook and loop disc option.

Finish & Detail Sanders- Finish sanders typically use a straight-line or vibrating action. They are sold in half sheet, third sheet and quarter sheet models as well as small palm style detail models that are often referred to as mouse, triangle or diamond sanders. Finish and detail sanders are available in all different shapes, but they all have the ability to get into tight places and corners.

Abrasive Resource laser cuts coated abrasive discs, sheets and strips in all different shapes, sizes and grits. If you need a hard-to-find sheet for a specific sander or application, please give us a call at 800-814-7358 and we’ll be happy to troubleshoot it with you!

For reviews on specific sander models, we referenced this article: http://extremehowto.com/all-about-sanders/

Back to Basics: Cloth Sheets

Most abrasive products, like sanding belts and sanding
discs, are ready to use right out of the box. But other sanding
supplies--like sandpaper or cloth sheets and rolls, usually need
to be cut to size before you are ready to sand with them. And
some abrasives benefit from being “broken in” before sanding
to improve their performance. Here are some “tried and true”
tips for handling cloth sheets:

• Cloth sheets can usually be torn evenly along the weave of the fabric backing
  by ripping carefully across the sheet from one edge to the other. Otherwise,
  a utility knife cuts nicely from the back of the sheet. Common sizes are
  4-1/2” x 5-1/2” and 3-2/3” x 9” for power sheet sanders.
  a
•  When sanding curved or irregular surfaces, your cloth sanding sheet will
  benefit from a little additional flexing. Just pull the back of a 9 x 11 sheet
  over the edge of a benchtop or machine table. Then turn it 90 degrees and repeat.
  a
• Even if you choose the most popular name brand of abrasive, it won’t do
  you any good if you continue to sand with that cloth sheet once it’s dull.
  Change out your cloth sheet with a new one as soon as you notice it is
  no longer sharp. Dull abrasive sheets require more energy to remove
  stock, decreasing your productivity. In addition, they will contribute to
  a poor finish on wood.
  

Most cloth backed sanding sheets have a flexible, J weight fabric backing and
are available in grits 40-400. They are seen as a general purpose abrasive for
wood or metal and can be used by hand or attached to high speed vibrating
sanders. Abrasive Resource also converts custom-sized cloth backed sheets
for specific industrial or artistic applications. 

For more information on cloth sheets, visit the Abrasive Resource website 
or call us at 800-814-7358.

Sanding Diamond Willow

Tools that will do the job: Scrapers, chisels, knives (no folding blades though--it's too hard to see what you're doing through the blood) and of course, sandpaper. All sharp tools must be used in such a manner and direction that the hand not holding the tool is out of danger.

Procedure: Remove the bark from the diamonds. This can be done most effectively with a rounded blade such as a gouge chisel or a knife. Whatever the tool, do not cut too deeply into the diamond area. Traces of bark in the deepest recesses enhance the final appearance. If you prefer to remove all traces of bark, you must take care not to cut to a depth that exceeds the diamond's special coloration.

Next, smooth the overall surface to whatever degree practical using a scraper, rasp, block plane, broken glass (an old Boy Scout trick) or other tool that lends itself to the purpose.

Sanding follows and this is the most important element in creating a good-looking finish.

Sandpaper Recommended: You will need standard Aluminum Oxide Production Paper. Grits needed are 100, 120, 220 & 320. The paper should be tri-folded for easy gripping during use. 90% of the sanding has to be done with the 100 grit paper, so resist the temptation to go to the other grits until you have smoothed the wood to the greatest degree possible with the 100-grit.

Coating: This can be done with whatever finish you prefer except that polyurethane is not recommended. Tung oil finish works very well for everyone.

Submitted by Holace Nelson of Holly Industries

What is the difference between open coat and closed coat sandpaper?

CLOSED COAT







Closed Coat means that close to 100% of the backing on a coated abrasive product is covered in abrasive grain. Closed Coat products are more aggressive and cut faster because the grit particles are grouped more closely together.They also provide the best finishes because there are no gaps between the grains. You receive the full benefit of the work that the abrasive grain is capable of doing.


SEMI OPEN / OPEN COAT

Semi-Open and Open Coat means that there is more space between grain particles on the abrasive product. Semi-Open Coat usually refers to about a 30% reduction in the amount of grain on the backing and Open Coat usually means that there is about 50% coverage. Semi-Open and Open Coat products have less grain on the backing, which results in less cutting power per grit designation...they are not as aggressive as a Closed Coat abrasive product. In addition, Semi-Open and Open Coat products have gaps in their grain coverage, so the finishes they provide are not quite as even and will tend to fall on the coarse end of the finishing scale for that particular grit.

So what’s the bottom line?

You should always use a Closed Coat abrasive unless there is a reason for you not to. The main reason to switch to an Open Coat abrasive is that the material you are sanding or grinding is soft or gummy. Soft materials are soft woods like Pine, Fir, Spruce, Larch, Cedar, Cypress, Redwood, Tamarack, and Yew. Soft metals include Aluminum, Brass, Bronze, Copper, Magnesium, Titanium, and Zinc. When you attempt to sand these types of materials with abrasives manufactured with a closed coat, the areas between each grain will load up with sanding swarf. Eventually it will load up to the point that it’s taller than the grain and will completely cover the grit. If you continue to sand with a “loaded” abrasive, you will burn both the belt and most likely your workpiece. This is where Semi-Open and Open Coat abrasives are most useful.

By spacing out the grains on the backing of an Open Coat material, you create room between individual grains which will help to reduce the amount of sanding swarf stuck between the grains. You can then use compressed air, a rubber cleaning stick or even the movement of the running sander to help dislodge the swarf from the abrasive. This will enable you to sand soft materials for longer periods of time and with better results.

Woodworkers that only sand cherry, oak, ash or other hardwoods usually don’t experience any problems sanding with an Open Coat abrasive, but you would benefit from using Closed Coat abrasives for your hardwoods and reserve Open Coat materials for soft woods only. You sacrifice life, speed and quality when you use an Open Coat abrasive product on a bare hardwood finish for no reason. This may not be practical for smaller woodworking shops that work with different wood varieties every day, but certainly something to consider.