Warm Forging
In cold forging of parts with relatively
com-plex geometries from high-carbon and alloysteels, forging pressures are
extremely high andthe ductility of the material is low. As a result,short tool
life and defects formed during forginglimit the economic use of the cold
forging processes. Consequently, in manycases,warmforging, i.e., forging at
temperatures below recrystallization temperature, is commonly used[Altan et
al., 1983]. For warm forging, steels areusually heated between room temperature
andusual hot forging temperature. The normal temperature range is considered
to be 1110 to 1650 F (600 to 900 C). An exception is the warmforging of
austentic stainless steels, which usually are forged between 390 and 570 F
(200 and300 C) [ICFG, 2001b]. The process may be in-terpreted broadly as
thermomechanical process-ing at elevated temperature to achieve the fol-lowing
advantages:
●A reduction in flow stress. This
isapplicable,in particular, to high-alloy steels. As a result,tool stresses and
forging loads are reduced(Fig. 17.26).
●Greater ductility of the forged part. This
al-lows more complex shapes to be forged.
●A reduction in strain hardening. This
mayreduce the number of forming and annealingoperations.
●Greater toughness of the forged part
●Improved accuracy as compared to hot
forg-ing
●Enhanced product properties through
grainrefinement and controlled phase transfor-mations in heat treatable steelsAs
an example, variations of tensilestressandductility (as indicated by reduction
of area) withtemperature are shown in Fig. 17.26 for 1045steel. It can be seen
that the tensile stress doesnot decrease continuously with temperature.There is
a temperature range, in this case, at ap-proximately 400 to 800 F (205 to 425C),wherein forging would not be
recommended.Warm forging requires determination of the op-timum forging
temperature and the suitable lubricant. Selection
ofwarmforginglubricantshasproved to be especially difficult. The factor
thatlimits the use of warm forging is that the technology is still undergoing
development, particularly in aspects of surface treatment,lubrication,and
tooling.Tooling for warm forging is similar to that forcold forging, with some
modifications made inthe die to allow increased temperatures, internaldie cooling,
and venting of coolants.
(Cold And Hot Forging: Fundamentals And Applications ,Taylan Altan,Gracious Ngaile,Gangshu Shen p.233)
***There is no old definition...
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Continuous transfer
In this continuous method of transfer line , the work pieces are moved continuously at constant speed.This requires the work heads to move during processing in order to maintain continuous registration with the work part.
For same types of operations
this movement of the work heads during processing isn’t feasible.It would be difficult ,for
example , to use this type of system on a machining transfer line because of
inertia problems due to the size and the weights of the work heads .In other
cases , continuous transfer would be very practical . Example of its use are :
Packaging , beverage bottilng operation , Manual assembly operations and simple assembly tasks.
Continuous transfer systems are relatively esay to design and fabricate and also can achive a high rate of production.
Continuous transfer systems are relatively esay to design and fabricate and also can achive a high rate of production.
(Computer Integrated Manufacturing , M.S. Ganesha Prasad,B.S. Raju , p.19)
***There is no old definition...
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Utilization and Availability
To construct a disparity ratio, we must define each of its components of utilization and availability. First, however, we must define a WOSB. he SBA definition of a small business, for
federal contracting purposes, varies by industry. In manufacturing, mining, and wholesale
trade, the definition is based on the number of employees. Firms with fewer than 500 employees are considered small in manufacturing, and firms with fewer than 100 employees are considered small in wholesale trade. Annual revenue is used to define small firms in many other
industries, such as construction (less than $28.5 million), retail trade (less than $6 million)
and service firms (less than $6 million). he subset of small businesses that are women-owned
comprises those of which at least 51 percent is owned by women. One can imagine scenarios
in which the number of women-owned or small firms is overstated because firms wish to present themselves that way in order to receive preferential treatment in SBA programs. One can
also imagine that characteristics of firms can change over time without any intent to “game the
system,” through firm contraction and expansion, ownership changes, mergers, and the like.
his report does not address these errors of classification.
We vary our measures of utilization and availability to create four basic kinds of ratio.
First, we derive disparity ratios based on the dollar value of awarded contracts. hese are shown
as 1 and 3 in Table 2.1. Second, we use number of contracts awarded to measure utilization.
hese are shown as 2 and 4 in the table.
A key decision in the derivation of disparity ratios is determining how to estimate availability. he first (and broader) method estimates the share of WOSBs in the economy. he
second estimates the share of WOSBs among the set of ready, willing, and able firms. Which
method is appropriate depends on the mechanisms thought to be at work. Disparity ratios do
not measure discrimination itself, they measure the difference between men and women in
some dimension, in this case, in winning federal government contracts. he difference could
be due to a number of reasons, only some of which are discriminatory. For example, women
might be more interested than men in industries where the federal government does not spend
a lot of money, or they may be less interested in working with the government. hese factors
suggest that the second method—focusing on ready, willing, and able firms—might be the
correct one to use. Discrimination in the awarding of contracts, however, might result from
women business owners being less likely to bid on contracts. his would not be detected if the
pool of available firms consists only of firms that have demonstrated their interest by bidding
on contracts. Again, the disparity ratio can only measure the difference; it cannot explain it.
he SBA requested that RAND define the population of firms that are ready, willing,
and able to perform federal contracts in two ways. he first is the population of all firms in the
economy (disparity ratios 1 and 2 in Table 2.1). he second is the population of firms that have
registered as potential bidders for federal contracts (ratios 3 and 4 in the table). hus, in this
report, we compute disparity ratios four ways: by contract-dollars and number-of-contracts
ratios in which the population of ready, willing, and able firms is essentially all firms, and by
contract-dollars and number-of-contracts ratios in which the population of such firms is all
firms that have registered as potential bidders for federal contracts.
(The Utilization of Women-Owned Small Businesses in Federal Contracting
,Elaine Reardon,Nancy Nicosia,Nancy Y. Moore, p.4)***There is no old definition...
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