Tolerances requirements

Figure 2.40 shows the initial detailed design including the tolerances required on each component in the stack to achieve the 0.2 mm assembly tolerance, (not included is the dimensional tolerance on the fuel port block of 12 0.05 mm which is set by the... 

It is probably obvious at this point that the molecular weight distribution of a resole is an extremely important characteristic. It has major influence on such important performance capabilities as cure speed, viscosity, green strength development (or prepress), assembly time tolerance, required application rates. 

During the selection of the number of hidden layer neurons, the desired tolerance should also be considered. In general, a tight tolerance requires that the selected network be trained with fewer hidden neurons. As mentioned earlier, cross-validation during training can be used to monitor the error progression, which subsequently serves as a guideline in the selection of the hidden layer neurons. 

Determine tolerance requirements that are expected in the performance of the product. Shrinkage characteristics of the selected plastic should be as small as possible so that tolerances can be anticipated with a reasonable degree of accuracy. 

Adaptation of metal tolerances to plastics is not advisable. With plastics reaction to moisture and heat, for example, is drastically different from metals, so that pilot testing under extreme use conditions is almost mandatory for establishing adequate tolerance requirements. Also important to control cost is that close tolerances should be indicated only where needed, carefully analyzed for their magnitude, and proven out as to their usefulness. 

Typical values for the clearances are given in the standards, and are discussed in Section 12.5.6. The clearances and tolerances required in practical exchangers are discussed by Rubin (1968). 

Tolerances the processing cost increases with the tolerance requirements. Not all dimensions are so easily controlled and one can distinguish three tolerance classes the tolerance also depends on the thicknesses ... 

Figure 3-1—Vertically Suspended Pump Drivers Tolerances Required for the Driver Shaft and Base...

Tolerance requiring more of the substance to produce the same pleasurable effects... 

Figure 31 — Vertically-suspended pump drivers - tolerances required for the driver shaft and base...

Low-temperature cooling limits are specified for each month of the year in the various states of the United States. Gasoline must meet these low-temperature limits for water tolerance before it can be marketed and sold. In addition to gasoline, water tolerance requirements also exist for jet fuel, diesel fuel, and heating oil. 

Construction considerations and the tolerances required were in accordance with recommendations in Refe. Al 0 and Al 2. Details of the calculations performed are presented in Appendix G,4. 

Metal tolerance can be defined as the ability of a plant to survive on soils that are toxic or inimical to most other plants because the soils contain elevated levels of one or more metals. This definition of tolerance requires us to be able to show (a) that the soil is toxic and (b) that a particular genotype or species can grow better on this soil than others. The toxicity of the soil can be inferred from the reduction in species diversity, or from direct tests in which plants are grown on the soil and their survivorship assessed however the causes of the toxicity (metals or other possible causes) cannot so easily be determined. Again, tolerance of the soil may be suggested by the survivorship of plants on the soils in which other plants perish (Bradshaw, 1952 Watkins and Macnair, 1991) whether this is tolerance of the metals present in the soils or other factors cannot be assumed without more detailed experiments. 

Generally recognized as safe (GRAS) Designation by the USFDA that a chemical or substance (including certain pesticides) added to food is considered safe by experts, and so is exempted from the usual FFDCA food-additive tolerance requirements. 

Understand and measuring melt flow or heat behavior of plastics during processing is important.487 It provides a means for determining whether a plastic can be fabricated into a useful product such as a usable extruded extrudate, completely fill a mold cavity, provide mixing action in a screw plasticator, meet product thickness tolerance requirements,... 

Thermoplastics have non-Newtonian melt flow characteristics it means that their viscosity will change dependent on their velocity or the amount of shear that occurs in the melt (Chapter 1). This non-Newtonian characteristic is a key in thin wall molding. As in any molding setup one cannot just simply ram the melt into the cavity. It s flow characteristic, gate size as well as position, and venting have to be balanced in order to obtain the desired structural part and meet tight tolerance requirements. 

Downstream of the die, the extrudate (melt) is calibrated, cooled and packaged by an array of ancillary auxiliary devices including vacuum calibrators, water tanks, cooling rolls, haul-offs, cutters, and winders (Chapter 18). Upstream of the die, a melt pump may be interposed between the extruder and the die to produce a more uniform extrudate. The exact selection and arrangement of these component parts of an extrusion system will depend on the end product and tolerance requirements that have to be met.25 27> 33> 143 196>476... 

Solid profiles can be simple flat plate dies with finished land geometry and pre-land dimensions determined by experience and trial in conjunction with sizing plates. If hollow shapes are extruded, supports are necessary, and tubing applications can have inflation air holes. Most of the profile dies, particularly those used in long production runs, require precision dies to meet very close tolerance requirements. 

The wear parts of pumps and valves are usually highly alloyed because of the dose tolerances required. Valves are usually 12Cr trimmed (seat and stem) for all temperatures. Pump impellers (and often pump cases as well) are 12Cr for temperatures above 550° F (288 C). 

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