Abrasives Spotlight

Commodity Group Description

An abrasive is a material, often a mineral, that is used to shape or finish a workpiece through rubbing which leads to part of the workpiece being worn away. While finishing a material often means polishing it to gain a smooth, reflective surface it can also involve roughening as in satin, matte or beaded finishes. The finish on the final workpeice is determined by the size of the grit used in the abrasive. Grit size typically runs from coarse (16 - 24 grit), medium (36 - 60 grit) and fine (80-120 grit). Superfine grits run from 150 and higher. Grinding wheels usually will be between 24 and 100 grit. Honing stones and jointing stones and other polishing abrasives will be 150 grit and higher. Coarse grit is used for fast, aggressive stock removal and finer grits for less stock removal but better surface finish.

Common uses for abrasives include grinding, polishing, buffing, honing, cutting, drilling, sharpening, lapping, and sanding. Abrasives are designed for various purposes and applications (metallic vs. non-metallic). Natural abrasives are often sold as dressed stones, usually in the form of a rectangular block. Both natural and synthetic abrasives are commonly available in a wide variety of shapes. The two most common classes of abrasives are "bonded" and "coated" abrasives, such as blocks, belts, discs, wheels, sheets, rods and loose grains.

Bonded abrasives

A bonded abrasive is composed of an abrasive material contained within a matrix. This matrix is called a binder and is often a clay, a resin, a glass or a rubber. This mixture of binder and abrasive is typically shaped into blocks, sticks, or wheels. The most usual abrasive used is aluminum oxide. Also common are silicon carbide, tungsten carbide and garnet. Artificial sharpening stones are often a bonded abrasive and are readily available as a two sided block, each side being a different grade of grit.

Grinding wheels are cylinders that are rotated at high speed. While once worked with a foot pedal or hand crank, the introduction of electric motors has made it necessary to construct the wheel to withstand greater radial stress to prevent the wheel from flying apart as it spins. Similar issues arise with cutting wheels which are often structurally reinforced with impregnated fibers. High relative speed between abrasive and workpiece often makes necessary the use of a lubricant of some kind. Traditionally, they were called coolants as they were used to prevent frictional heat buildup which could damage the work piece (such as ruining the temper of a blade). Various shapes are also used as heads on rotary tools used in precision work, such as scale modeling.

Bonded abrasives need to be trued and dressed after they are used. Dressing is cleaning the waste material (swarf and loose abrasive) from the surface and exposing fresh grit. Depending upon the abrasive and how it was used, dressing may involve the abrasive being simply placed under running water and brushed with a stiff brush for a soft stone or the abrasive being ground against another abrasive, such as aluminum oxide used to dress a grinding wheel.

Truing is restoring the abrasive to its original surface shape. Wheels and stones tend to wear unevenly, leaving the cutting surface no longer flat (said to be "dished out" if it is meant to be a flat stone) or no longer the same diameter across the cutting face. This will lead to uneven abrasion and other difficulties.i

Coated abrasives

A coated abrasive comprises an abrasive fixed to a backing material such as paper, cloth, rubber, resin, polyester or even metal, many of which are flexible. Sandpaper is a very common coated abrasive. Coated abrasives are commonly the same minerals as are used for bonded abrasives. A bonding agent (often some sort of adhesive or resin) is applied to the backing to provide a flat surface to which the grit is then subsequently adhered. A woven backing may also use a filler agent (again, often a resin) to provide additional resilience.

Coated abrasives may be shaped for use in rotary and orbital sanders, for wrapping around sanding blocks, as hand pads, as closed loops for use on belt grinders, as striking surfaces on matchboxes, on diamond plates and diamond steels. Diamond tools, though for cutting, are often abrasive in nature.ii

Loose Abrasives

Another form of abrasion is a process called sandblasting, which uses sand, glass beads, metal pellets, copper slag and dry ice in an operation which forcibly propels a stream of abrasive material against a surface under high pressure to smooth a rough surface, roughen a smooth surface, shape a surface, or remove surface contaminants.

Abrasive Materials

The most important property of an abrasive is its hardness. For abrasive grains to effectively cut, they must be significantly harder than the workpiece material. They can be grouped based on their hardness into two categories: conventional abrasives and superabrasives.

Conventional abrasive materials have been used by man since the advent of machining. They are made of materials that exist naturally on Earth, and they are abundant and cheap. Conventional abrasives can suitably machine most materials.

Superabrasives are much harder than conventional abrasives. Since they are much more expensive, they are used when conventional abrasives will not suffice.

Common abrasives are listed below.

Conventional

  • Aluminum oxide (Corundum)
  • Silicon carbide
  • Emery
  • Pumice
  • Sand
  • Steel abrasive

Superabrasives

  • Diamond
  • Cubic Boron Nitride (CBN), Borazon
iii

Industry Analysis

The US abrasives manufacturing industry includes about 300 companies with combined annual revenue of about $4 billion. Major companies include the abrasives divisions of 3M and Saint-Gobain (Norton). The industry is highly concentrated: the 50 largest companies generate more than 80 percent of revenue. iv

Demand is projected to reach $5.3 billion in 2011based on strength in the electrical/electronic product, motor vehicle and aerospace sectors. Nonmetallic abrasives will outperform metallic types. Improved production across the total manufacturing sector is expected to support the expansion in demand for abrasive products from the middle of the five year period to 2015. However, demand conditions will vary significantly across the key downstream markets. The demand for abrasives in the building and construction market is projected to average solid growth, stemming from the cyclical recovery in the housing market and continued solid demand from the highway construction market, and the gradual upswing in the commercial building market from 2012.v

Larger abrasive companies can make large investments in new technology. Small companies compete by specializing in products for particular manufacturing functions. Metalworking businesses that are large consumers of cutting tools and abrasives are making tool suppliers accountable for productivity. When awarded business, the supplier agrees to improve the customer’s efficiency by a certain percentage. Also, the pressure for greater machine uptime, shorter delivery times and smaller lot sizes are creating various options for quick-change tooling in the market.

Top Industry Users

  • Electrical/Electronics
  • Aerospace (Engine and Airframe)
  • Automotive manufacturing
  • Building and Construction
  • Highway construction
  • Metal Fabrication Environments

Key Items in the Commodity

Grinding Wheels, Dressing Tools, Sharpening stones/sticks, Cut-off Wheels, Sanding Discs/Pads, Polishing Discs/Pads, Sandpaper, Shot, Grit, Sand, Abrasive Belts

Abrasived

Key Cost Drivers

Raw Material Costs, Special Design Requirements, Performance Requirements

Strategic Sourcing Considerations

Because both cutting tools and abrasives are used to shape and finish a workpiece, often for production parts, they are typically linked in tooling programs and thus have similar strategies. In many cases, cutting tools and abrasives share a common distributor base.

Most manufacturing operations have a few common objectives:

  • Increase production
  • Reduce inventories
  • Reduce the number of suppliers

To help achieve these objectives your strategy should take into account the geographic location of your supply base relative to your production facility. In certain cases, you can negotiate a corporate pricing agreement directly with the manufacturer and have each facility serviced by a local distributor. This will allow you to have consistent pricing across multiple locations but still maintain the service level required to enable a close working relationship with the supplier. This will help to keep inventory levels down and allow them to offer product improvements at the point-of-use to increase efficiency and productivity. Many manufacturing plants rely heavily on their suppliers to provide the product expertise, so it is important to source a significant amount of volume to as few suppliers as possible so that they have the proper financial incentive to provide the technical services that will help drive down cost, eliminate waste, and increase productivity.

Another consideration is to understand your abrasive buy in terms of the abrasive application. If you separate Maintenance, Non-Production and Production or Blueprint Driven Tooling you can identify possible cost benefits. In addition to piece price savings, process improvements should be a requirement of any suppliers selected.

  • Other Considerations:
    • Tool life
    • Cost/cost per manufactured part
    • Quantity Price breaks
    • Standard packs
    • Minimum order quantities
    • Lead time
    • Geography
      Are you sourcing for a single plant location, or across multiple locations in diverse geographical areas?
    • Freight
      Where will material be shipping from?
    • Standardization
      Is there an opportunity for the same tool or same manufacturer brand in multiple operations within a single plant, or across multiple plant locations?

  • Understand Impact of sourcing changes on finished part quality and tolerances
    • PPAP requirements must be understood
    • Tool tests are critical when changes are made to the manufacturer

  • Blueprint or Custom Abrasives versus Standard Abrasives
    • Ensure that Blueprint change process is in place and understood
    • Incent suppliers to offer standard abrasives wherever feasible
      • Include suppliers early on the design phase.
    • Sourcing strategies will vary depending upon the specific situation.
      • If you are able to use standard abrasives, you usually have virtually unlimited choice of suppliers, from large on-line catalog houses like Grainger, MSC and McMaster Carr, as well as a myriad of local distributors that can meet your needs.
      • When your applications require specials and blueprint items, your choices are more limited. Usually, you’ll be dealing directly with the manufacturer or a very limited number of distributors.

References

  1. "Abrasives" Wikipedia. n.d. Web. September 2010.
  2. "Abrasives" Wikipedia. n.d. Web. September 2010.
  3. "Abrasives" Wikipedia. n.d. Web. September 2010.
  4. "Abrasives Manufacturing Industry Profile." First Research. Hoover's, Inc. 30-August 2010. Web. September 2010.
  5. "Abrasives and Sandpaper Manufacturing." IBISWorld. IBISWorld, Inc. 2-June 2010. Web. September 2010.
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