Push processing

Soon after the patents cited above were issued, publications about the new types of corotating extruders and their applications began to appear in increasing numbers. The secondary literature also cites further publications [24 to 35] from the period between 1951 and 1974, many of which were authored by the licensors Bayer, i.e., predominantly R. Erdmenger and the licensee Werner und Pfleiderer, i.e., H. Herrmann. These publications increasingly pushed process engineering and the various uses of the co-rotating extruder. 

ASA films, such as Kodak Tri-X Pan for black and white prints or Ektachrome for color slides, are suitable for many applications. These films can be exposed at 800 or 1600 ASA and push-processed in a high-contrast developer. A combination that has found favor in many laboratories is that of Kodak Tri-X with the Diafine two-bath developer (1), which provides an ASA of 1600. In general, black and white film has a finer grain and is suitable in most situations, the exceptions being doublelabeling procedures in which both fluorophores are to be photographed simultaneously or the preparation of color slides for presentations. 

The ESI MS method yielded results to identify isothiazolium salts 62 and 63 (05SUC211). The aqueous methanolic solution of the salts gave by application of this spray method intensive signals of the cation (ESI pos.) and accordingly the anions (ESI neg.). The determination of the molar mass and the total formula are possible. Information about the structure of the cations could be obtained by using the ion-molecule-push-process. The cations decomposed in the typical fragmentation pathway are formed in Scheme 81b. 

Same as in level 2, but in addition there is a shift from a pure manufacturing Push Process to a hybrid Push-Pull system. 

Push/pull view PuU processes are initiated by a customer order and push processes are initiated and performed on the forecast of customer orders. 

A push process conforms to a conventional supply chain management system going through typical stages in sequence. As shown in Figure 3.2, orders arrive at or after the demand cycle but always before the planning and procurement cycle and process is activated by a forecast or demand plan. Both raw and packaging materials are stored before production and products are manufactured to stock. The order fulfilment is achieved from the inventory of finished products. 

Push/Pull View The processes in a supply chain are divided into two categories, depending on whether they are executed in response to a customer order or in anticipation of customer orders. Pull processes are initiated by a customer order, whereas push processes are initiated and performed in anticipation of customer orders. 

All processes in a supply chain fall into one of two categories, depending on the timing of then-execution relative to end customer demand. With pull processes, execution is initiated in response to a customer order. With push processes, execution is initiated in anticipation of customer orders based on a forecast. Pull processes may also be referred to as reactive processes because they react to customer demand. Push processes may also be referred to as speculative processes because they respond to speculated (or forecasted), rather than actual, demand. The pusWpull boundary in a supply chain separates push processes from pull processes, as shown in Figure 1-5. Push processes operate in an uncertain environment because customer demand is not yet known. Pull processes operate in an environment in which customer demand is known. They are, however, often constrained by inventory and capacity decisions that were made in the push phase. 

L. L. Bean executes all processes in the customer order cycle after the customer order arrives. All processes that are part of the customer order cycle are thus pull processes. Order fulfillment takes place from product in inventory that is built up in anticipation of customer orders. The goal of the replenishment cycle is to ensure product availability when a customer order arrives. All processes in the replenishment cycle are performed in anticipation of d and and are thus push processes. The same holds true for processes in the manufacturing and procuranent cycles. In fact, raw material such as fabric is often purchased six to nine months before customer demand is expected. Manufacturing itself begins three to six months before the point of sale. The processes in the L. L. Bean supply chain break up into pull and push processes, as shown in Figure 1-6. 

All processes in the customer order and manufacturing cycle at Ethan Allen are classified as pull processes because they are initiated by customer order arrival. The company, however, does not place component orders in response to a customer order. Inventory is replenished in anticipation of customer demand. All processes in the procurement cycle for Ethan Allen are thus classified as push processes, because they are in response to a forecast. 

Demand forecasts form the basis of all supply chain planning. Consider the push/pull view of the supply chain discussed in Chapter 1. All push processes in the supply chain are performed in anticipation of customer demand, whereas all pull processes are performed in response to customer demand. For push processes, a manager must plan the level of activity, be it production, transportation, or any other planned activity. For puU processes, a manager must plan the level of available capacity and inventory, but not the actual amount to be executed. In both instances, the first step a manager must take is to forecast what customer demand will be. 

A Home Depot store selling paint orders the base paint and dyes in anticipation of customer orders, whereas it performs final mixing of the paint in response to customer orders. Home Depot uses a forecast of future demand to determine the quantity of paint and dye to have on hand (a push process). Farther up the supply chain, the paint factory that produces the base also needs... 

The interest in bioethylene, i.e. green ethylene, has pushed process development and commercialization of the ethanol-to-ethylene process. The units that produced ethylene in this way until the 1980s were quite small, at most 50000 tonnes of ethylene/year, compared to today s announced units, which are considerably larger, Braskem 200000 tonnes/year and Dow-Crystalsev 350000 tonnes/year, respectively. 

Part shape. Tooling considerations and the approach to moving material will determine what kind of shapes can be produced. Shapes can be defined by their dimensionality. Pull/push processes, for example, can usually only produce two-dimensional shapes with a constant cross section because material is pushed through a die. Push processes... 

Push processes lend themselves to the production of parts that are small-to-moderately sized and that have a high degree of detail and complexity. They are also prime contenders in situations where exacting performance requirements can be obtained by using different raw materials. Squeeze processes cannot easily produce a high level of complexity or detail, but they can be used to produce large parts that are very strong and that have excellent surface appearance. 

Processes that push material into a closed mold are widely employed. In total, push processes offer the most overall versatility for general part manufacturing. 

Fig. 6 Resin transfer molding represents a hybrid approach to producing parts. It incorporates some elements of "push" processes with traditional compression molding.

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