Tolerance grades

Figure 2.10 ISO tolerance grades for machining processes (adapted from Green, 1992)...

The tolerance grades are interpreted using standard tables (BS EN 20286, 1993) for conversion into dimensional tolerances. However, the tolerance grades do not take into consideration different materials machined or the complexity of the component being processed. 

BS EN 20286 1993 Part 2 - ISO System of. Limits and Fits - Tables of. Standard Tolerance Grades and Limit Deviations for Holes and Shafts. London BSI. 

Dimensions to tolerance grade G7/h6. Reference ISO 286 (ANSI/ASME B4.1). 

Dimensions to tolerance grade H7/h6 for axially split pumps, an additional tolerance to allow for gasket thickness + 75 pm / 0.003 in. 

Dimensions and tolerance (A, Do, h, SDR, SIDR) measured in accordance with ASTM D 2122, ISO 3126 or EN 1636-5. The International Standards ISO 11922 with Part 1-metric series and part 2-inch based series specified tolerance grades for outside diameter, out-of roundness, and wall thickness of polyolefin pipes for conveyance of fluids. They are manufactures with nominal diameters and nominal pressure in accordance with ISO 161-1 and nominal wall thickness in accordance with ISO 4065. 

Plywood requirements—includes wood species used, synthetic repair requirements, veneer grades, veneer layers and thicknesses, panel grades with respect to end-use, adhesive bond requirements, panel constmetion and workmanship, scarf and finger-jointed panels, dimensional tolerances, moisture content, and packaging and loading... 

Depending on their stmctural type, PEPE oils are stable up to 300—400°C ia air. Pure oxygen ia a test bomb at 13 MPa (1886 psi) at temperatures up to 400°C was tolerated with no ignition (43). Densities at 20°C vary from 1.82 to 1.89 g/mL, and viscosities from 10 to 1600 mm /s. The pour poiat for low temperature operation usually ranges from —30 to —70° C, and the viscosity iadex varies from about 50 for low viscosity grades up to 150 for more viscous oils and considerably higher for fully linear polymers (43). 

Electronic-Grade MMCs. Metal-matrix composites can be tailored to have optimal thermal and physical properties to meet requirements of electronic packaging systems, eg, cotes, substrates, carriers, and housings. A controUed thermal expansion space tmss, ie, one having a high precision dimensional tolerance in space environment, was developed from a carbon fiber (pitch-based)/Al composite. Continuous boron fiber-reinforced aluminum composites made by diffusion bonding have been used as heat sinks in chip carrier multilayer boards. 

Working-grade thermometers, conventionally called industrial resistance thermometers, are generally smaller than the SPRT element and may be as small as 2.5 mm in diameter and 10 mm in length. These are available in various 0°C resistances, eg, 100, 200, and 500 Q. They are available as unsheathed elements or in a wide variety of sheaths and enclosures, both standard and custom. They are relatively inexpensive. They are usually made to be interchangeable, without relying on iadividual cahbration, within limits of 0.25 K or closer upon special order. A typical tolerance statement for a precision-class industrial resistance thermometer is... 

Commercially, HEC is available in a wide range of viscosity grades, ranging from greater than 500 mPa-s(=cP) at 1% soHds to less than 100 mPa-s(=cP) at 5% total soHds. Because HEC is nonionic, it can be dissolved in many salt solutions that do not dissolve other water-soluble polymers. It is soluble in most 10% salt solutions and in many 50% (or saturated) salt solutions such as sodium chloride and aluminum nitrate. As a rule, the lower substitution grades are more salt-tolerant. 

Because of their low thermal conductivity, high temperature capability, low cost, and neutron tolerance, carbon materials make ideal thermal insulators in nuclear reactor environments. For example, the HTTR currently under construction in Japan, uses a baked carbon material (Sigri, Germany grade ASR-ORB) as a thermal insulator layer at the base of the core, between the lower plenum graphite blocks and the bottom floor graphite blocks [47]. 

---