SECTIONING SUPPLIES FOR SAMPLE PREPARATION
The most versatile and economical sectioning method is abrasive cutting. A thin, rapidly rotating, consumable abrasive wheel produces high-quality, low-distortion cuts in times ranging from seconds to several minutes, depending on the material and the cross-sectional area. This technique is almost universally applicable. Important parameters in abrasive cutting are wheel composition, coolant condition, and technique. Abrasive wheels consist of abrasive grains (alumina, silicon carbide, boron nitride, diamond) bonded together with either resin or rubber or a rubber-resin combination, or metal. The abrasive grains become rapidly worn out during cutting of hard materials and must be continuously replaced by newly exposed grains. When cutting hard materials, a cutting wheel with a soft binder (soft cutting wheel) is chosen to promote a fast removal of used grains and the continuous exposure of new abrasive grains, thus always maintaining a sharp cutting edge. On the other hand, a cutting wheel with a hard binder (hard cutting wheel), is recommended for soft materials, since a fast exchange of abrasive particles is not necessary. Although soft cutting wheels are more rapidly consumed than hard cutting wheels, they are more suitable for harder materials, since their cutting action is considerably faster because of the renewed exposure of fresh abrasive grains. Other criteria for the selection of suitable abrasive wheels are the grain size and the concentration of the abrasive particles, as well as the thickness of the wheel. The concentration depends on the special cutting task and on the material to be sectioned, the binder, and the abrasive grain size. The abrasive concentration determines the removal rate and the durability of the abrasive wheel. A wheel with a high concentration and coarse abrasive particles is generally recommended for small areas of contact, while a cutting wheel with low concentration is typically used for large areas of contact. Depending on the type of material to be sectioned, cutting wheels of different compositions should be used, and their selection is dictated by hardness and ductility of the material to be cut
Table A.1 Application of cutting wheels
Cutting wheel: abrasive/binder
Steel, ferrous materials, hardened steels
Cubic boron nitride (CBN)/bakelite
Nonferrous metals, hard metals
Silicon carbide (SiC)/bakelite
Hard and tough materials, cermets, ceramics
Hard and brittle materials, ceramics, minerals
lists some common materials and their appropriate cutting-wheel/binder combinations. Cutting wheel machines are available with high or low speed, with or without a feeding device, and even with precisely guided sample holders. The machines must always be equipped with a cooling system to prevent excessive heat that might affect the microstructure of the specimen; the coolant is ordinary water, to which a corrosion inhibiting agent can be added.
An important part of sectioning is a proper wheel or blade selection. Like everything in materials preparation, there are tradeoffs, but thorough evaluation of your needs and processes, the best abrasive wheel or precision blade for your application can be selected. Abrasive wheels come in a wide variety of diameters and bond systems. Select the wheel designed to cut your material, however, you can select a wheel up or down in bond strength to achieve longer wheel life or better surface finish. Precision blades are best matched first to the material type, then to blade diameter, abrasive type, and concentration.
ABRASIVE CUT-OFF WHEELS
Metallurgical Supplies providing Aluminum Oxide Abrasive & Silicon Carbide Cut-Off Wheels for the best possible burr free materials sectioning. Recommending to use this wheel on hard, medium, and soft metals, ferrous alloys, and tool steels. Sample preparation Cut-Off Wheels are available in 6"" (152 mm), 7"" (178 mm), 9"" (229 mm), 10"" (250 mm), 12"" (300 mm), 14"" (350 mm), 16"" (400 mm), 17"" (432 mm) and 18"" (455 mm) diameters and are engineered to provide the best possible burr free materials sectioning
PRECISION CUT-OFF WHEELS
Metallurgical Supplies providing precision series of Silicon Carbide and Aluminum Oxide Abrasive Wheels for high-speed precision sectioning of non-ferrous materials and hard and medium-soft ferrous materials. Sample Preparation Cut-Off Wheels Rubber Bonded is engineered for high-speed precision sectioning. Available in 5"" (127 mm), 6"" (152 mm), 7"" (178 mm) and 8"" (203 mm) diameters in (Al2O3) for hard and medium-soft ferrous materials; (SiC) for non-ferrous materials.
DIAMOND WAFERING BLADES
DIAMOND WAFERING BLADES - Metallurgical Supplies providing Diamond Blades and CBN (Cubic Boron Nitride) blades which are the preferred blade type when precise sectioning is needed. They also perform better than traditional abrasive blades when cutting certain materials, especially very hard materials. Diamond Wafering Blades which are available in 3"" (76 mm), 4"" (102 mm), 5"" (127 mm), 6"" (152 mm), 7"" (178 mm) and 8"" (203 mm) diameters. These range of blades covers all types of materials including basic metals, ceramics, glass, soft/gummy materials, alloys, composites and much more.
- High Concentration (Metal Bonded)
For general use with ferrous and non-ferrous alloys; copper, aluminum, metal matrix composites, PCB boards, bones, thermal spray coatings and titanium alloy.
- Low Concentration (Metal Bonded)
Low Concentration for brittle materials such as ceramics, glass, carbides and other heat resistant materials
- Resin Bonded (High Concentration)
For hard, delicate materials or brittle materials (cannot be used at low speeds. High speed only 950 RPM's or higher.)
- CBN (Metal Bonded)
CBN (Cubic Boron Nitride), recommended for iron and cobalt-based alloys, nickel-based super alloys and lead-based alloys.
COOLANTS - Metallurgical Supplies line of coolants are designed to dissipate heat and remove swarf from the cutting point. Proper cooling is critical to the sectioning process.
DRESSING STICKS - Metallurgical Supplies line of dressing sticks help keep your diamond tools sharp and efficient. If not frequently dressed, a diamond tool can glaze over and begin tearing instead of grinding, creating friction and possibly damaging the tool as well as the project you're working on. Metallurgical Supplies dressing sticks reduce these risks by keeping diamond tools properly dressed. Use a silicon carbide dressing stick in a coarse grit to help dress conventional vitrified wheels. Use silicon carbide dressing sticks in softer grades and fine grit sizes for helping to dress diamond wheels. An aluminum oxide dressing stick in any grit size can work well on diamond profile wheels.