Dimensional accuracy

Furan hot-box resins are used in both ferrous and nonferrous foundries (66,67). In this process, resin and catalyst are intimately mixed with dry sand and then blown into heated metal boxes containing a cavity the shape of the desired core. In seconds, the surface of the sand mass hardens and, as soon as the core has cured sufficiently to be rigid and handleable the box is opened and the core removed. Automotive cores with exceUent dimensional accuracy and high strengths are made via this forty-year-old process. 

Pulsed ECM (PECM) may be a promising way to improve dimensional accuracy control and also to simplify tool design. Accuracies as fine as 0.002 mm have been quoted using current pulse lengths of ca 0.2 to 2.0 ms, at current densities of 55 A/cm. Pulse offtimes are from 1 to 2 ms (7). 

Iron is the preferred metal for casting steel and nonferrous metals are used in smaller amounts. Most castings are made in green sand molds, ie, uncured molds of sand, clay, and water. However, the use of sheU mol dings is growing, because such mol dings permit reproducibUity of castings with close dimensional accuracy. In addition, the simplicity of equipment procedures reduces costs. 

When dimensional accuracy is required in a specific application the effect of water absorption should also be considered. Manufacturers commonly supply data on their products showing how the dimensions change with the ambient humidity. 

Radio and television uses largely arise from the ability to produce components with a high level of dimensional accuracy coupled with good dielectric properties, high heat distortion temperatures and the availability of selfextinguishing grades. Specific uses include coil formers, picture tube deflection yokes and insert card mountings. 

PEs, as other polymers, exhibit nonlinear behavior in their viscous and elastic properties under practical processing conditions, i.e., at high-shear stresses. The MFI value is, therefore, of little importance in polymer processing as it is determined at a fixed low-shear rate and does not provide information on melt elasticity [38,39]. In order to understand the processing behavior of polymers, studies on melt viscosity are done in the high-shear rate range viz. 100-1000 s . Additionally, it is important to measure the elastic property of a polymer under similar conditions to achieve consistent product quality in terms of residual stress and/or dimensional accuracy of the processed product. 

Cutting fluids provide benefits such as extended tool life, dimensional accuracy and good surface finish, all of which contribute to high rates of production. Almost invariably, the coolant that adheres to workpieces is relied on to protect ferrous components against corrosion while they are waiting further machining or assembly operations. 

The most usual forms of platinum or, more frequently, of the platinum alloys containing 5 or 10% of rhodium, are thin protective sheaths contoured to conform with the shape of the underlying refractory. Sheaths of this type, generally 0-25 mm to 0-65 mm thick, are widely employed to protect tank lips, skimmer blocks, stirrers, thermocouple pockets, etc. More substantial —thicknesses-up to 2-5 mm thick —are used to protect orifices whose dimensional accuracy must be maintained to a high degree. 

Processing is extremely important in regard to tolerance control in certain cases it is the most influential factor. The dimensional accuracy of the finished product relates to the process, the machining accuracy of mold or die, and the process controls, as well as the shrinkage behavior of the plastic. 

Tolerance Thermoformed products lack the dimensional accuracy of processes such as injection and compression molded products. 

Material Characteristics Strength and Stiffness Toughness Short-Term Heal Resistance Long-Term Heal Resistance Environ- mental Resistance Dimensional Accuracy in Molding Dimensions Stability Wear and Frictionat Properties Point Subtotal Cost Point Total... 

This process is used to produce intricate, thin-section parts with great dimensional accuracy, fine detail, and very smooth surfaces. All ferrous and nonferrous alloys can be cast in investment molds. Investment casting begins with expendable wax patterns that are assembled into clusters, then coated with a series of successively coarser ceramic slurries. The assembly is then fired in a furnace to dry and harden the ceramic shell and to melt out the wax, leaving a cavity into which molten metal is poured to form the casting. 

Due to the nature of the test method, quality by design is an important qualification aspect for in vitro disolution test equipment. The suitability of the apparatus for the dissolu-tion/drug-release testing depends on both the physical and chemical calibrations which qualifies the equipment for further analysis. Besides the geometrical and dimensional accuracy and precision, as described in USP 27 and Ph.Eur., any irregularities such as vibration or undesired agitation by mechanical imperfection are to be avoided. Temperature of the test medium, rotation speed/flow rate, volume, sampling probes, and procedures need to be monitored periodically. 

Lost-foam sand casting Sand (expendable but recyclable) pattern is consumed Ferrous and nonferrous As above plus no need for parting line better surface finish than conventional sand casting increased dimensional accuracy Increased cost, added process steps As above... 

Inspecting Capsule Components. Prior to cleaning, capsule components are inspected for dimensional accuracy and machining flaws. 

The properties of the interface metal/solution. Cast iron corrodes because of exposure of its graphite to the surface (graphitic corrosion), which is cathodic to both low-alloy and mild steels. The trim of a valve must always maintain dimensional accuracy and be free of pitting and hence it should stay cathodic to the valve body. Hence, in aggressive media, valve bodies are frequently chosen of steel rather than cast iron. Because of increased anodic polarization, low-alloy steel (Cr and Ni as noble components) is cathodic to normal steel in most natural media. Accordingly, steel bolts and nuts coupled to underground mild steel pipes, or a weld rod used for steel plates on the hull of a ship, should always be of a low-nickel, low chromium steel or from a similar composition to that of the steel pipe.7... 

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