MRP Ⅱ with JIT Mixed Mode Comparison and Discussion

ORIENT ACADEMIC FORUM
Ⅱ with JIT Mixed Mode Comparison and Discussion
MRP
YOU Qi
College of Management, Southwest National University, 610041
Abstract: At present, many enterprises in the production operation of the implementation
process, MRPII choice in the end, or a choice JIT (Just In Time) method of generating a puzzled In
practice MRPII and JIT how to understand the benefits and shortcomings , how to understand the
relationship between the MRPII and JIT, how to organically combine the two, will help enterprises
change the mode of production and is conducive to the improvement of production efficiency.
Keywords: MRP , JIT, mixed mode
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MRP , Advantages and Disadvantages of the Means of Production
1.1 production operation mode of MRP. Manufacturing Resource plan referred to as MRPII Planning, it
is the abbreviation of Manufacturing Resource, it is material Requirements Planning MRP (Materials
Requirements Planning) as the core, it covers all areas, activities of production enterprises is a kind of
effective utilization of resources, production management ideas and methods. MRPII changed "material
requirements planning" (mainly for the production of inventory control), the mode of operation of
financial subsystem and production subsystem, adopting "for execution plan -" feedback - effectively to
produce logic, the resource planning and control [1]
According to 14 manufacturing enterprise survey the city of chengdu, after using MRPII, generally in
the following aspects: the stock funds obviously reduced 12-35%; Capital turns 50-160 percent increase,
Stock to error rate reduced 2.4%, A shortage of 50-70% reduction, Labor productivity 5-11% increase;
Overtime work 10-30% reduction, Schedule of delivery rate reached 90-95%, Production costs decline
5-15%, Purchasing cost of around 6%, 8-10% profit increase, Inventory rate dropped 4-8%. In addition,
can make the management personnel from the complex "trivial" extricate affairs, really focused on
improving management level, to solve the problems in the management of the key and substantial
1.2 There are two malady aspects MRP
in the survey also found that MRP in actual production operation also some problems. (1) in the
infinite resources condition is good, but in limited resource conditions often have certain time and plan,
so plan sometimes difficult to execute. MRP using prior given in the capture in actual production and
delivery time not consistent period do not reflect reality, plan, MRP exaggerated in the executive
function, leading to higher products, stocks, high and low delivery ability. According to MRP is piece
production, more variety small batch production, three ways of water production and single production
in practical production factory, one may exist various management mode and the product mix
production.. MRP cannot handle customer's various choices and execution of customer orders. All
sorts of interference factors, such as worker absence, malfunction parts are short of scrap and plans.
Once appear disturbance MRP difficulty. MRP is a centralized system, adopting concentrated
single database, by a central computer processing, thus causing the system response time long, slow, the
system reliability. (2) the MRP
system itself is not the "continuous improvement of flexible
mechanism. MRP system operating performance, depending on the accuracy of the data, a good
MRP system, its inventory information must be timely update, material single must accurately reflect
the production technology, product structure must be fully describe the resources needed for accurate
process, because of this, MRP system of evaluation index system is the pursuit of stock 90% accuracy,
BOM accuracy is more than 90%, etc, these are MRP
rating criteria. However, in the actual
production of enterprise to reach the standard and the production of uncertain factors, so as to plan and
execute deviation sex, MRP index system is hard to adapt to the modern flexible production mode.
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JIT Production Mode Pros and Cons
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2.1Just-in-time production mode (JIT) can In Time as, Japan is the Toyota motor company In the 1960s
executes a production mode, basic thoughts on production mode can be summarized as "In times of need,
according to the need of the quantity required to produce the products" [2], namely through the
production plan and control and inventory management to achieve a "no inventory" production systems,
or to minimize inventory of production systems.
Just-in-time production operation mode benefits: in just-in-time production mode, the enterprise general
taken before the advocacy of "loose ford before production, after tight" that paragraph of time is
personnel, equipment and production line for parts, after a period of spare parts, a staff of emergency
products. This caused the production process of logistics unreasonable phenomena, especially in
inventory and shortages, line or not obvious trait, or after a boot on the mode of production, and caused
serious waste of resources. Toyota's just-in-time is much less batch, short cycle of the means of
production, eliminate inventory, optimize production logistics, reduce the waste objective [3].
2.2 Just-in-time production mode core is a no inventory of production systems, or to minimize inventory
of production systems. This includes "kanban" developed a series of specific methods, and gradually
formed a set of unique production management system [4]. Just-in-time production mode with
just-in-time production, first exposed the overproduction and other aspects of the waste, and equipment,
personnel, etc, to reduce cost, improve the control plan and simplified. In production control technology,
the basic principles of just-in-time is in need of time, the number of parts, or production need immediate
production, product. It will traditional production process, the first working backward procedure, after
the delivery process according to "kanban" forward procedure take goods, “kanban” system is
just-in-time production site control technology at the core, so greatly reducing inventory and production
cost, improve the economic efficiency of enterprises and on time delivery.
2.3 JIT evils: (1) it is only applicable to repetitive manufacture type. JIT way more suitable for large
repeat manufacturing environment, this is due to the relevant operational mode JIT primarily in
repetitive manufacture industry development, it is to those products faster, update the upgrade to apply
strong enterprise. (2) JIT operations enterprises and suppliers are closely, and emphasized the
relationship with a single supplier and established long-term cooperation relations, the purpose is to
ensure the timely supply of quality and delivery. But modern market economy is a contract is one of the
many business relationship, establish the supplier for supply and demand relation mode, so enterprises
and suppliers is probably not a single supply and demand relation. (3) lack of long-term plan JIT, not a
long-term plan system JIT, just emphasize a process or phase of implementation and control, waste
materials and quality control.
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Ⅱand JIT Integration
MRP
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3.1Although
in production and MRP JIT operations, but the pros and cons of two different kinds of
manufacturing plan and control method can completely incompatible and can complement each other.
Although MRP
basically is a plan is basically, JIT production is a kind of control method. The
weakness is MRP execution of the workshop, and this is controlled; the strong JIT The strong place is
MRP, long-term comprehensive plan, which was JIT weakness. MRP in philosophy, in emphasis
on integration of means plan; JIT philosophy emphasizes on improving, attaching importance on means
of control, can form a completely new hybrid manufacturing and management mode. They mixed mode
of philosophy is the integration of technology improvement, it means plan and control.
3.2Look from content is committed to JIT and MRP in appropriate amount of material supply and
manufacture of different products, and is
MRP effectiveness of supply and demand to "on" and
"supply" JIT, Both in the factory to balance work load, in order to reduce production bottleneck, both
early stage and reduce inventory reduction, reduce scrap and provide products according to customers'
needs, which is to establish the intercommunity and JIT mixed mode
MRP provides operation
theoretical basis.
3.3In the actual production of MRP and JIT philosophy and operational ideas mixed mode in complex
single production environment, product structure is complex, makes the material requirements planning,
MRP by computer can realize complex logic, and considering the changes in the early period, the
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different control and execution workshop operation that must be regularly in order, information
feedback control, can guarantee
MRP production management mode, therefore, MRP than JIT is
more suitable for single production type. In the production of subsystems execute way, can use the result
that JIT, MRP plan effectively smoothly. If you need to consider the design products according to
clients' requirements, and therefore, in order to shorten the design larger workload from design to
production cycle, and further to CIMS mode has design and manufacture of parallel integration. In batch
production environment, MRP and JIT mixed model can well mixed mode combined form. In this
mixed mode, MRP for processing plan and orders issued, the management function, JIT for workshop
executive. In repetitive production environment, material and flat, concise sheet in stable equilibrium,
MRP production rate in this single, stable production environment, for long-term material plan, JIT
model used in the production process control.
Therefore, the MRP and JIT mixed mode can be used in the process of planning and implementation
of production management. Of course, the MRP and JIT mixed mode not only used in production
process, it still can be applied to the distribution, financial, inventory, logistics management, etc., and
still , production, sales for the integration of "integration", financial management mode of production is
useful.
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With the JIT Mixed Mode of MRPII Implementation and Ideas
With mixed mode, MRPII JIT to enhance the efficiency of production and operation cost reduction. Its
implementation process mainly in three aspects:
4.1 JIT production planning with MRPII in combination of level. The drive mode embodies in MRPII
production plan for every link, MRPII production under the plan, plan is mainly based on sales forecasts.
But sometimes not very accurate sales forecast, may cause the hand many inventory, on the other hand,
many emergency orders needs a lot of coordination in frequent adjustments. Plan. Each plan adjustment
involve levels, slow, slow reaction. According to the customer's requirements and JIT production, keep
pulling production and demand, as long as JIT synchronous transfer to a final, other processes can
automatic production information change, so can make up deficiencies. MRPII However, it also has
defects JIT production need only instructions now, do not know what the future, how to produce output
production, which can arrange to meet customer needs, resources needed to arrange production plan
MRPII. So the supply of materials with mixed mode of MRPII JIT production resources allocation as
MRPII planning and JIT production is specific instructions.
4.2 The plant with MRPII and JIT at material control level. The production according to the production
plan MRPII material distribution list, then this list as production cost accounting vouchers. In under the
condition of less frequency distribution. But could face many varieties, small batch production mode,
face frequent distribution mode, MRPII often occur in production and inventory of high. And JIT just
can respond more variety and small batch, high frequency distribution of material. But no material
function of settlement JIT, if each line is to settle, the number of JIT workload, and extend the time of
delivery, MRPII materials can be very good solution to this problem. MRPII system in the product line
is a "feedback" module function, namely, in accordance with the referral model combining BOM list
determined material consumption, and use this mode than originally one fold MRPII pattern more easily.
In a single MRPII production operation, often happen in the operation of contradiction, production and
logistics spend a lot of time to confirm the material and increase production quantity, so the cost of
operation. But with the feedback function JIT mode can order the change of demand and material
inventory completely symmetrical and matching, solve the problem of logistics relative to zero, the
backlog inventories. Therefore, MRPII and JIT mixed mode of operation in materials distribution, which
is helpful to improve the logistics efficiency, but also to supply and demand data accurate production
system and balance.
4.3 JIT material purchasing and MRPII in combination of level. In information age, the market
demand change quickly upgrade and high, but the single MRPII management mode can not meet the JIT
production, material procurement and distribution MRPII arrangement often leads to higher inventory
and lack of material, so constantly revised purchasing plan, this waste of manpower and material
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resources. And so the application of MRPII and JIT mixed mode can be calculated using MRP a cycle
longer purchasing plan and material distribution is subject to JIT operations, it can solve the problem.
Anyhow, JIT production with MRPII both organic combination of production management is the future
trend of development. Therefore, we should study and explore more advanced management mode,
which is conducive to our manufacturing management innovation and development.
Author introduction:
You Qi southwest national university, college of management associate professors.
References
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[1]. WuZhenYe production and operation management of southwest jiaotong university press 2006.2
[2].
, ERP, MRP program-controlled principle and application of tsinghua university press 2002.6
[3]. HuangWeiWei production and operation management of renmin university of China publishing
house 1997.6
[4]. GoyalSK. DeshmukhSG. Ritique AC, w.t. can drop in on Manufacturing time.
ProductionManagement Operation & 1992,12: (1),
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