Plastic inserts

Many of the plastics available today may be bonded to rubber provided that the thermal and mechanical properties of the plastic are compatible with the process conditions required for the bonding process. Fully saturated polymers such as polyethylene and polypropylene are not generally considered to be suitable for the process but can be successfully moulded to cured rubber. Examples of this can be seen on military vehicles where such mouldings work as aerial bases. 

The use of plastic substrates is increasingly common, especially in suspension system bushes, where its use reduces weight and eliminates the need to swage or calibrate the outer insert. An interesting development is the use of plastic interleaving, eliminating the need to expand the inner tube. It should be noted that this was the subject of a BTR AVS patent. 

The most commonly used plastic for inserts is polyamide 6,6. This is used in both natural and glass-filled forms. A wide variety of grades are available but care must be exercised in their selection. Properties of modulus, impact strength and heat resistance should be optimised in the selection process. In production it is nsefni to monitor the filler content and type together with the glass transition temperatnre. 

The market has also seen the introduction of a new material that bonds directly to rubber. This appears to very attractive unless you sell bonding agent There are some snags. The price is quite high and its use in the UK is not viable except for very low weight items. For successful bonding the rubber must contain some SBR. 

Plastic inserts can, and should, be delivered in clean containers and manufactured from grades that contain little or no internal release agents or process aids. This will allow the inserts to be coated with bonding agents without further treatment (see later). Polyamide grades shonld be selected for their mechanical properties and especially with regard to the temperature at which distortion can occnr. 

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A basic dmm is often supplemented by blow-molded plastic inserts that fit closely into the interior cavity. These inserts generally are provided with molded fittings for filling and sealing. The combination, which is referred to as a composite dmm, enhances the fiber dmm for additional appHcations,... 

The term erosion-corrosion is used to describe the increased rate of attack caused by a combination of erosion and corrosion. If a fluid stream contains suspended particles, or where there is high velocity or turbulence, erosion will tend to remove the products of corrosion and any protective film, and the rate of attack will be markedly increased. If erosion is likely to occur, more resistant materials must be specified, or the material surface protected in some way. For example, plastics inserts are used to prevent erosion-corrosion at the inlet to heat-exchanger tubes. 

Figure 5 The Costar Transwell system with a cell monolayer grown on a porous polycarbonate filter that is mounted onto a removable plastic insert forming the apical chamber. Two other systems, (1) the Costar diffusion chamber system, where a filter-grown (Snap-well) cell monolayer is sandwiched between two chambers of equal volume and the bathing solutions are agitated and/or gassed and (2) filter-grown cell monolayers mounted in a two-chamber rotating cylinder device (Imanidis et al., 1996), are not shown.

Plastic a pre-moulded plastic insert of differing properties to the moulded polymer can simplify tools and lead to cost savings. 

With the improvement in equipment design and the manufacture of higher-powered instruments have come the welding-related applications such as staking, metal-in-plastic insertion and spot-welding. 

Standard valve trims are defined by standards such as API 600 and API 602. Elastomer or plastic inserts may be specified to achieve bubble-tight shutoff. Valve manufacturers may be consulted for recommended trims. 

Preassembled parts Preassembled parts may contain components made from heat-sensitive substrates (e.g., plastic inserts, wiring). In contrast to the conventional method, where individual components are coated prior to assembly to avoid heat damage, UV powder coating permits the manufacturer to fully assemble a part prior to coating. 

In an attempt to eliminate some of these problems, a new centrifuge (Centritech ) was specially designed for mammalian cell separation (Johnson et al., 1996). This centrifuge operates with Rf > 0 and generates a centrifugal field intensity up to 320 g. It operates in a closed system and contains a presterilized and disposable plastic insert, which eliminates the... 

Bennett, P.M. Genome plasticity insertion sequence elements, transposons and integrons, and DNA rearrangement. Methods Mol Biol 266 (2004) 71-113. 

The weapon s detractors point to the working clatter of the bolt as a drawback to its silent role. I can only point out that plastic inserts were used on the later models where these metal surfaces met. 

Inspection of the punches is carried out during the manufacturing of the tablets when plastic insertions are used. Inspections ensure that the plastic insertions are intact, i.e., that no loss or damage to the discs has occurred. 

An apparatus for simultaneously coating a plate with two adjacent layers of different adsorbents was accomplished by placing a plastic insert into a commercial spreader, thus forming two independent chambers. For this reason, combinations of two adsorbents, such as cellulose, silica gel, alumina, charcoal, silicic acid, magnesium silicate, etc., as a function of the sample were used. Then, the two eluents systems were optimized for the two development directions, e.g., 2-D separation of some ketones on a bilayer (charcoal/silicic acid) with benzene-ether-acetic acid (82 9 9, v/v) in the first direction (on charcoal) and with benzene-ether (85 15, v/v) in the... 

A flat plastic insert is part of the meter assembly which consists of four analog meters for observing current and voltage for different functions of the system. 

With the gas collection reservoir, you have an O-ring cap seal with a Teflon-faced plastic insert. Pierce the insert with a hypodermic syringe and draw off some of the product. Usually, you put this gas through GC (see Chapter 30, Gas Chromatography, for particulars). 

Portions of ca. 30 g were transferred into cleaned glass bottles provided with a screw cap and a plastic insert. A PTFE ball was added in each bottle to allow the user to re-homogenise the material before opening. 

The powder obtained was dried again for 2 h at 60°C and homogenised for 24 h in a PTFE-lined mixing drum. The powder was then transferred into a dry-air glove box connected to a gas purification system. At this stage, the moisture content of the white clover was below 3% (w/w). Clean, brown-glass bottles provided with a PTFE ball for rehomogenisation were filled with ca. 25 g of material and closed with plastic inserts and screw-caps. 

When sufficient wet materials was collected, it was freeze-dried, ground in a zirconia ball mill and sieved to pass 125 pm apertures. The resulting powder was collected in a mixing drum and homogenised by continuous rotation under dry Ar over two weeks. Cleaned brown glass bottles were filled with approximately 5 g of material and closed with screw caps and plastic inserts. A PTFE-ball was added to facilitate later re-homogenisation in case segregation would occur. 

Bottling operation was carried out after a verification of the bulk homogeneity by XRF. The bottling procedure was performed manually after an additional period of mixing of 2 days, a first series of 20 bottles was filled and immediately closed with screw caps and plastic inserts. Series of 20 bottles were hence filled, alternating with re-mixing of the powder (2 minutes). The bottles were stored at ambient temperature. 

Drums, crates and trays are designed in such a way that when stacked in multi-tiered layers each interlocks with the one below. Trays, for example, can have plastic inserts or integral designs at each comer to support the tray above. 

In another example, ] a problem with poor physical properties of molded fluoroplastics was overcome. Transfer molded material was found to have low modulus of elasticity above 150°C and was prone to irreversible cold flow. The solution involved embedding a metal or plastic insert as a core material in the mold. The choice of the core material depended on the end use performance requirements. 

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