Abrasive products coated in roll, disc and abrasive belt format are used in the main industrial sectors such as the automobile industry, the nautical ndustry, wood and varnishing, construction, and painting and decoration,among others.
These abrasive materials are widely used and high consumption. In fact, we can affirm that in the majority of cases in which there has been a process of painting a surface, it has previously been subjected to a preparation process in which a coated abrasive product has been used.
Coated abrasive products are used in most surface preparation
processes for painting
Because the market offers a multitude of options for abrasives transformed into rolls, abrasive discs and sanding bands, when choosing the most appropriate one, we must take into account some considerations:
Accessibility to the work area, comfort and convenience for the user during the sanding operation, the type of material to be sanded, the sanding operation to be performed and the price variable are the main factors that condition the use of a type of sandpaper or other roll.
According to the type of support or backing material of the abrasive rolls wecan classify them into:
Sandpaper rolls with flexible or rigid paper support. Optimal for any universal sanding and all kinds of metal, wood, varnish, resins and solid surface parts among others
Sandpaper rolls with sponge paper support. Excellent for sanding profiles, moldings
and curved surfaces
Sandpaper rolls with velcro paper holders. Necessary for manual sanding with the help of coves and claws.
Sandpaper roll with flexible, semi-flexible or rigid fabric support. Use for universal sanding of all types of materials, in which the performance of the abrasive takes priority over the final finish.
Sandpaper rolls of non-woven fiber (scotch). Employees for surface shading.Abrasive products coated in roll, disc and abrasive belt format are used in the main industrial sectors such as the automobile industry, the nautical industry, wood and varnishing, construction, and painting and decoration, among others.
Rolls of steel wool sandpaper. Used to achieve an excellent finish on varnished and difficult to access surfaces, which in turn will be finished in high gloss.
Aspects to consider when choosing discs and sheets
1 Format of the abrasive disc:
When choosing the abrasive disc we must take into account:
The type of fastening of the disc to the plate, among which are:the velcro system, the self-adhesive system or the system without fixing by the support part.
The outer diameter and the number of holes. Variables that must match the diameter of the plate and the number of holes in it.
2. Types of operation to perform.
Coarse sanding of surfaces (grains 40, 60 and 80) corresponds to discs with a support of rigid paper or polyester film.
Intermediate sanding of the surface (grains 100, 120, 150, and 180): it corresponds to discs with support on semi-rigid or flexible paper depending on the needs of adaptation to the surface that we are going to sand.
Fine sanding (grains 220 to 600) we will opt for discs with a flexible paper backing or polyester film.
Finishing sanding (grains from 600 to ). In this case, we will need sponge-backed discs or polyester film.
3. Embossing level: type of material to be sanded
In this case we can speak of two clearly differentiated types of materials:
Embossing materials: for which we have abrasive discs that have a spaced or semi-spaced distribution of the mineral, in addition to a layer of anti-embossing stearate.
Slightly clogging materials: this time we will use abrasive discs with a semi-spaced or closed mineral distribution depending on the type of material to be sanded.
4. Hardness of the material to be sanded
Hard and tough materials, such as steels or alloys. We must use abrasive discs with ceramic ore, compact ore or zirconium ore. On occasions in which the development of the work will be carried out in areas with high temperatures on the surface, we must opt &#;&#;for abrasive discs that contain a layer of active lubricant.
Highly hard materials such as stone, glass or ceramic. In this case, we will use abrasive discs with silicon carbide ore.
Materials with a medium or low hardness. Use abrasive discs with aluminum oxide mineral. Maybe you're interested: Wind turbine repair: how to rebuild damage to materials
In this case, we will focus on wide bands, those whose measurements are greater than 600 mm and up to 1,600 mm.
These types of bands are used in the wood and varnished sector for sanding flat pieces.
When choosing an abrasive belt there are different variables to consider:
1. The appropriate mineral for the type of material we want to sand:
Zirconium ore should be used to sand hardwoods in rough calibration or surface sanding operations.
Aluminum oxide is the most common mineral used for sanding wood, veneer and melamine, in any sanding operation.
Silicon carbide ore is used to sand fiber boards, particle boards and solid surface
plates.
As for the sanding of primers, sealants and bottoms, it is possible to choose between the use of the aluminum oxide ore or silicon carbide, depending on the type of
bottom and the sanding operation, although in general the silicon carbide is The most
employed.
2. The distribution of the mineral is linked to the level of embouchure and hardness that the sanded surface presents.
Therefore, it is necessary to take this particularity into account when opting for one type of band or another.
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Distribution of spaced ore: use for sanding soft and/or resinous materials prone to rapid swelling of the abrasive belt.
Distribution of semi-spaced ore, for sanding wood, veneers, melamines, as well as primers and sealants in varnishing.
Closed ore distribution. Use on fiber boards and chipboard boards.
3. Existence of stearates to reduce embossing and improve the level of finish.
In this way, it is possible to choose between different types of bands:
Bands without stearate, used for general sanding of wood, veneer, melamines and
boards.
Bands with stearate, used for sanding putties, bottoms and solid surface in general.
4. Take into account whether the abrasive belt is antistatic or not.
Since it is a feature especially relevant in the case of continuous sanding and varnishing lines, in which the pieces are sanded and immediately after they are anchored and finished.
Although, the antistatic bands prevent the dust released from sanding from electrostatic energy and easily adhere to the piece before varnishing.
5. Support used for abrasive tape.
Keep in mind that the choice of the type of support is determined by the type of operation to
be performed.
Calibration and sanding operations use bands with rigid cotton fabric support, or cotton with polyester or polyester only if the aggressiveness of the calibration operation requires it.
Coarse or intermediate sanding operations, which involve the use of bands with rigid
paper support weight F which allows proper planning of the sanded surface.
Fine sanding or finishing operations, use bands with semi-rigid paper support weight E
that allows transmitting the flexibility and sanding pressure of the sanding units with
sectioned skid group.
Superfinishing sanding operations, use narrow belts with polyester film supports to
achieve uniform sanding and free of emboss marks.
To choose the appropriate abrasive bands we must consider the appropriate mineral, the level of embossment and surface hardness, the existence of stearates, if the band is antistatic and the support used for it
At Abracom we are highly specialized in the customized transformation of coated abrasive products for the industry: rolls, discs and abrasive bands. We have the specific abrasive for each material and sanding operation. We advise our clients to recommend the abrasive products that best suit their needs. Contact us and we will advise you.
Selecting the right abrasive and using that abrasive correctly for metal fabrication applications and welding can make all the difference in maximizing productivity and minimizing cost. Still, with today&#;s tight deadlines, fabricators are tempted to use whatever abrasive is handy without considering which is the best one for the application. Some might even ignore some fundamental rules of grinding safety. The results can be lower performance of finished products, increased grinding and finishing costs, and lost productivity.
It is important to realize that abrasive products come in various grades, which some manufacturers designate as good, better, and best (which is the scheme used in the tables in this article, in descending order: 1=best, 2=better, 3=good).
Metal fabricators who measure total grinding results and want to achieve the lowest overall cost for an application use the best abrasive products available for most of their work, reserving the use of the middle grade for high-productivity applications where only the abrasive cost is important. End users wanting the lowest initial cost are likely to select good abrasives but should be aware that such a choice may not be economical in the long run.
Fabrication and welding shop owners interested in determining total grinding results can work with their abrasive supplier to test and compare abrasives of various grades and alternative products from various manufacturers. Such tests, performed on-site, reveal relative abrasive cost based on price and wear rate and can even measure overall worker productivity based on a worker&#;s wages. Then, the relative abrasive cost can be added to the operator cost to determine the total grinding cost. What such tests typically show is that the most advanced (best) abrasive products usually last longer, work faster, make best use of the worker&#;s time, and often provide the most cost-effective choice.
The first step in processing a weld is grinding to take it down as much as possible (see Table 1). The amount of work required for this step depends on the hardness of the material, the type of weld, the welder&#;s skill, and a few other factors. For the most part, taking a weld bead down is done most cost-effectively with a right-angle grinder. For this application, the abrasives used on these tools can be fiber discs, flap discs, or smaller versions of these products, used for greater control or to deal with smaller work envelopes.
Fiber discs remove excess material from flat and contoured surfaces with a fast initial removal rate. A few tips:
Flap discs are good for removing heavy weld seams and excess material while providing a long service life:
Advantages of flap discs over a single-layered product include:
Whether using flap or fiber discs, higher-performance ceramic grain abrasives work best when powered by an angle grinder rated at more than 1,200 watts.
The second step is to remove the scratches created by the first step and to set the directional scratch pattern of the final product. It is very important to get below the rotary scratch pattern created by the grinder during the takedown step. If this pattern is not removed completely, deeper grind lines could appear when attempting to develop finer finishes. The abrasive to achieve this stage, a No. 3 finish, is a conventional 100- or 120-grit abrasive belt in the size required for the part (see Table 2).
For applications that require a No. 4 to No. 8 finish, it&#;s customary that the scratch depth, pattern, and direction are uniform across the surface of the product. To achieve such a finish, it&#;s common practice to use an abrasive with the same linear scratch pattern as the abrasive used in the previous step, starting with a medium-grit, nonwoven belt or wheel.
When a uniform directional scratch pattern is not a requirement of the final product, a rotary tool can do the job after taking the weld down. In this case, two abrasives of choice are a premium nonwoven unified wheel or nonwoven surface conditioning disc. Surface-blending discs conform to the contours and offer lower cut rates with finer finishing capabilities.
Controlled use of the disc at a 10- to 15-degree angle prevents random scratch patterns. A coarse-grade disc offers a blending capability that prepares the surface for polishing or a coating such as paint.
It can be advantageous to switch to a nonwoven product as soon as possible in the blending process. For example, deburring, blending, and finishing can be accomplished with one nonwoven product to reduce the number of discrete steps (see Table 2 and Table 3). A nonwoven product also provides a controlled, sustained finish while decreasing the likelihood of undercutting and gouging. The nonwoven product type also provides a cooler action to minimize the chance of warping or discoloration. Finally, it runs quieter and vibrates less.
Following few safety rules and general productivity tips can help improve the results:
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