Enterprise manufacturing resource planning MRPII principle (points)

A perspective,

Principle 1 for all manufacturing industry, effective planning and control the system framework is common.

Principle 2 a manufacturing factory is a separate entity, need to have a integration system and the collective cooperation to manage it.

Work plan and control:

Main production plan

ability

priority

Execution:

Supplier delivery

The workshop of the produce of the center

Machinery and equipment maintenance

Solve problems

Principle 3. Shorter lead times more effective plan is to make the most important factors.

Executive plan calls for solving the problems of the block production, not with inventory to offset problem with time to compensate for or buffer. To solve these problems by the whole manufacturing process of all personnel involved in the collective cooperation between.

Manufacturing is can control, and the payoff is tremendous. The success of the company to make to plan and execute balance development.

Second, the basic principle of inventory management

(a) the definition of inventory

Inventory include: product, production materials and maintenance before with materials

Principle 4. Manufacturing to all three control requirements for inventory effectively manage it.

1. Stock investment and customer service, I hope to have a balance between what kind of?

In a effective manufacturing control to executive management policy and have unexpected demand or supply interruption occurred, inventory holdings and its caused by service exist between a certain relationship. The lower inventories, arrears and inventory-optimal; and the more Inventories, the higher the better service.

2. Investment in inventory and change the production level of incidental between cost, I hope to have a kind of balance?

If production must XiaoShouLv response of the change of the wave, the big equipment ability, work overtime, lockout, employment, training and fired workers and other relevant expenses shall be exalted. Inventory can block these fluctuations.

3. Investment in inventory and issuing replenishments order to have what kind of balance between?

Frequent operation work or in small batch issue purchase orders can reduce many stock holdings. The result is that the high production adjustment and procurement costs, too many other operating costs and lost quantity discount.

4. Investment in inventory and cost of transportation between hope to have the kind of balance?

For example, for the hour to provide labor services and mobile workpiece material handling equipment is daily mobile workpiece demand is bigger overhead. Transportation way faster, the higher the cost.

(2) the function of the inventory

According to the function distinguish, inventory has five basic types:

1. The wave (demand and supply) inventory

2. Expected inventory

3. Batch inventory

4. Transportation inventory

5. Barrier inventory

Type of work can good place

Batch quantity for each manufacturing operations (namely the procurement decouple discount; reduce production

Automatic machine and assembly; Supply adjustment, material handling, clerical work

Business and users) and examination expenses, etc.

Demand-demand for unexpected volatility insurance increase sales; Reduce sinotrans, for

(security inventory) generation more expensive products, and customer service

, documents, telephone, cable, bag

Outfit and other fees.

Supply-fluctuations for supply disruptions insurance (i.e. decreases shutdown and add some, "alternative

Work, suppliers the lead time change) materials and goods transported into the; Increase sales

The level of production (that is to meet the season with some subcontracting, reduce, employment,

Section of sales, marketing and fired, fire insurance, training, the report

Pin) waste and rework expenses, etc. Reduce the

The equipment should be rich ability

The transportation to fill the distribution channels (that is, increase sales in road, reduce transportation, move

Branch warehouse and entrust the material) and packaging costs

Screen for disabled price mention arch barrier (that is, copper, reduce the material cost

Silver)

(3) the classification of inventory

Besides the function outside classification, inventory can also be according to the position in the process to classification

1, raw material: used to manufacture of components in finished products of steel, flour, wood and cloth or other material.

2, component: ready for investment products of the assembly parts or son the assemblies.

3, in products: the factory (or wait for homework processed in between the material and components.

4, finished product: ready for the production factory inventory holdings of finished goods or production plant in order to press a order to deliver goods to the customer's finish goods.

Principle 5, control requirements have really count Numbers, and not just easy to count Numbers.

(4) the cost of inventory

Decided to hold much inventory, make sure it each specific decided to the influence of cost. In inventory decision-making involved in the costs of the following categories:

1, ordering cost: ordering cost has two kinds: one kind is due to a purchase order to purchase materials supplier has cost; Another kind is to a factory orders because the costs of an.

2, inventory holding costs: include the company because their inventory and cost of everything that happened. Usually include the following for

A, scrap: because sales model and customer demand changes make the stock material can no longer pin and the cost of happened. In fashion, high technology and goods in the defense industry, this problem is sharp.

B, damage: stock supplies may damp, dry, for handling and dirty or in many other ways and no longer sell or damage can no longer available.

C, tax: many states, cities to class inventory tax. Some are according to the annual of a particular time of the stock investment, some of the average annual inventory according to investment to taxation.

D, insurance: inventory like other assets is same, want to cast, usually this is part of the insurance policy.

E, storage: store inventory needs a storage room, executives, operation personnel, material handling equipment, the necessary records, and so on. If there is no inventory, it won't happen the cost of these facilities.

F, capital: invest in stock of money just can't be used in other activities of the company. In fact, it could be to borrow the money from the bank. The cost of borrowing money or lose the chance to use the money is in the company of other USES opportunity, have to count the cost of capital for investment in inventory.

3, shortage cost: if customer order without the material available for delivery, may lose sales or may take place is called the shortage cost of the extra cost money. Deal with the workload of arrears order (shipping, invoice and inventory control of paperwork and add some) may be considerable.

4, ability association cost: and ability related cost includes some, sub-contract contract, employment, training, fired and downtime costs. When need to increase or reduce the ability or ability temporarily, too much or too will occur when such costs. Two basic law:

1) they should be the actual cash cost, not standard accounting cost.

2) they should be truly were being made a decision of the specific those fees.

In use cost data in a stock before decision making problems, must be specific to say, "where the savings will come from?" And "will save?" These two problems, convinced that the calculation to represent the actual real life situation.

There are two methods about the ABC basic law to keep in mind:

1, the degree of control:

A. to a kind of goods, as far as possible to kept under strict control, including the most complete and accurate records, at the highest level of supervision of the often review, from suppliers according to overall orders frequent delivery, a workshop on track to compress the lead time closely, and so on.

B. the b items, as normal control, including the good record and conventional attention.

C. c items, as far as possible, use the most simple control, such as regular visual inspection, simplified physical inventory records or only the most Jane sign law shows the stock has been added the order, with large inventories and order to avoid out of stock and arrange schedule workshop to low priority when.

2, inventory records:

A. a kind of goods required the most accurate, complete and detailed records, to frequently even real-time update records. The business documents, scrap loss, receiving and delivery of strict control is not may lack.

B. b items just normal record processing, to update, and so on.

C. c items, need not record (or only the most simple), to update, simplified to a large number of the count, and so on.

3, priority

A. in all activities to a kind of items to the higher priority to compressed ahead of its time and inventory.

B. b items only asked to normal processing, only when the key to the higher priority.

C. to c items to the lowest priority.

4, order process

A, a kind of goods to provide order quantity, carefully and accurate order point and MRP data. For computer data need artificial check, plus frequently review to compressed inventory.

B, b items, quarterly or when there is a major change review a EOQ and order point, MRP output by routine treatment.

C, c items do not request for EOQ or order point calculation. Often don't have planned the MRP order. Stock on hand is still very much the last year's supply are ordered. Use visual review, pile up, and so on.

Three, economic batch

(a) economic batch of the concept of value

Principle 6. Put the production adjustment number assigned to high value items to reduce its inventory, can easily low inventory items of compensation growth.

In many cases EOQ concept has no value. The calculation is no reason EOQ:

1, customer stipulated quantity (that is, for the order to produce goods)

2, operation by equipment capacity constraints batch (such as fine chemical products).

Three, the shelves of product life is short.

4, the tool life or need sharpening, modify, and so on, the operation time limit.

5, raw material in the batch quantity limit died.

(2) the basic concept of EOQ

The concept is applicable to the following circumstances EOQ:

1, the item in droves, or through the purchase or through the manufacturing and get complement, it is not continuously production comes out.

2, sales or use rate is uniform, and with the item's normal production rate is low compared, making the significant number of inventory and produce.

Manage manufacturing batch and purchasing batch this both is indispensable, because they often represent the largest single stock the role the part. Determine the skills of batch is this kind of management work of the good tool, but the actual workers professional know their application is actually in a bad situation for its good just as much as possible. When the production adjustment costs or ordering cost is high, the introduction of ordering cost and inventory EOQ held the balance of cost total cost to the minimum. But if you can lower production adjustment or order cost, can achieve better results.

Principle 7. The correct EOQ is good, but more short production adjustment is better than it.

Four, demand management

(a) the demand management range

Including the demand from the following:

1, the customers from home and abroad;

2, the company's other factories;

In other parts of the three, branch warehouse;

4, in place of the customer send pin in stock.

It will include the following activities:

1, the demand forecast;

2, the orders register;

3, a promise delivery;

4, and main program interface.

Demand will be involved in all kinds of materials including:

1, finished products;

2, as a product components;

3, repair a

In the most widely sense, demand management including planning warehouse address, from manufacturing source to warehouse alternative delivery methods, warehouse layout, material handling and assignments. General term actually for distribution.

(2) the characteristics of prediction

In the prediction of the techniques discussed before, know how to predict the general characteristics is important. The most important feature can be briefly described as follows:

1, predict will be wrong

2, the prediction of the error estimates of the enclosed is the most useful

Three, for larger items combination, some more accurate prediction

4, for a short period of time, some more accurate prediction

(3) the implementation of the forecast

Make the forecast has five main steps:

1 the purpose of the definition, forecast

2, to prepare data

3, choose techniques

4, make predictions (including estimate of the prediction error)

5, tracking forecast

Principle 10. Give each user a applies to the need to forecast.

The use of prediction in the following four aspects are obviously different.

─ ─ 1, horizon short, medium and long

2 ─ ─ cycle, weekly, monthly, and quarterly or once a year

3, review of frequency ─ ─ daily, weekly, monthly or longer

─ ─ 4, measurement unit money, pieces, hours, gallons, playing, and so on

(4) of its total business volume forecasts

(5) categories of products forecasts

The product is used to formulate group forecast the ability to plan, not be used to arrange other combination type. They are used to determine for every kind of main production facilities of the workers and the ability of the machine needs. An important objective of the product group forecast was to establish production level. This application using group forecast in the principle of individual items forecast.

(6) items prediction

Level of demand with the steady demand on behalf of mature products.

The demand of intermittent life cycle of representative in the early or late very low demand for goods and most of the repair parts.

That trend needs a relatively stable growth or down

Seasonal items each calendar year to peak experience ups and downs.

In addition, there are some special demand conditions, such as normal cyclical demand and the cyclical demand longer than a year,

(7) forecasting techniques

(8) the special prediction

For promotion and new products make the forecast for stability than items far more difficult to predict. Because very few new product is really the original, this prediction can often be a similar products according to the past experience.

(9) predict why not

Why not create forecast the result of success, the reason is not mysterious, there are six:

1, the prognosis is not the collective effort; And evaluation will be different from the past to the internal and external factors work requirements have the functional departments personnel participation. No "experts" for the job.

2, occurrence disillusioned; Accuracy is not realistic to want to cause refused to use forecast and not use forecast; Surprisingly, people keep this unrealistic hope to repeat this kind of vicious circle.

3, happen "do-it-yourself" abnormal psychology; Apparently "their predictions" is wrong, so we must to do it by yourself. Yesterday we is not so good, but the forecast tomorrow will be better.

4, people have different needs; Sales personnel need to extend to meet the challenge of the forecast, the financial plan must be managers is conservative and manufacturing must have a realistic attitude.

5, is unattended; Everyone hopes to predict will be right, know that it will be wrong, and forget it, thus lost to find out how it may be wrong and when it obviously need to be revised, the opportunity.

6, unnecessary project has been excluded. For trying to describe the products material list the components of options for or product to make demand forecasting is a waste of time.

(10) the demand of the source

Forecast, stock, and meet all kinds of customers to the needs of various materials shall be the dominant strategies such as principle of 14.

Principle 14. Less than the last moment as much as possible, don't put the inventory items in any specific site committee.

Five, * materials control: independent requirements

(a) inventory added

Principle 15. Correct answer a items when you need to order problems than sure how many goods is much more important.

Heavy order method:

1, two boxes of law: this system, a particular stock of goods at a predetermined amount is placed on the side (often put in separate the second box) not to contact, until the item's main stock being used up. When reserve supply is opened, namely have notice was sent to inventory control office and gave a replenishment of the order. (see "two simple methods to place orders")

2, visual evaluation method: periodically with visual FaHe of inventory level, after each evaluation in the inventory levels should be restored to a pre-defined existing stock and has ordered the maximum amount of the occasion to give the replenishment of the order. (see "two simple methods to place orders")

3, order collocation method (fixed ─ ─ order variable ordering cycle system) : when the delivery of the goods in a perpetual inventory records of the inventory decline to a pre-defined called order point level with a replenishment order (usually order for prior calculation good EOQ)

4, regular evaluation method (fixed ─ ─ variable order cycle system) : in the regular review, inventory records are periodically review, maybe once a week or once a month, and regular order make existing stock plus the total inventory quantity has returned to determine in advance of the highest level. (see "regular evaluation techniques").

5, material requirements planning (MRP) : in the MRP, material can meet the use of the materials according to the items for production plan in advance the quantity and the delivery schedule to order.

(2) the order of collocation method based

Note:

1, quantity (the EOQ) is usually fixed, and only when the expected there significant demand change will only be recount.

2, in fact, order point in too many cases are fixed and rare be checked. This chapter will put forward in the back a week in or longer intervals to update the order point technique, to keep them with the expected demand or early period of the change in coordination.

Three, two replenishment intervals between the order is not constant, it is with the utilization rate: the demand is higher, the short order interval (so named for ─ ─ fixed quantity of variable cycle).

4, inventory reserves part inventory is often thought to average up all the year round is the existing stock.

5, inventory of the periodic inventory quantity is equivalent to the full part in it just only be gathered into the existing stock is. On average, only half of the order will be all the year round in the library, because the assumption that the utilization rate is uniform.

6, average total stock plan is equal to the amount of the quantity and reserves half in stock.

(3) use visual method looking for order point

The required reserves is the major stock levels by the following elements of a function:

1, accurately predict demand ability

2, the lead time length

3 and accurately predict or control the lead time ability

4, the size of the order

5, hope the level of service

─ ─ some statistical methods to not being fettered practical points and methods, free of ─ ─ to application can be quite effectively be used to determine the actual useful reserves in stock. This chapter below a few section discusses methods in the industry in a wide range of applications and the professional manager is of help.

Principle 16. Because of uncertainty can't be eliminated, order collocation method require reserves in stock.

(4) prediction error estimate

Predict the standard deviation error to use the following steps:

1, a week from the actual sales minus the predicted that offset value

2, the deviation of the square

3, the square summation of deviation

4, determine the mean square deviation

5, the mean square deviation will prescribe, reached the standard deviation

(5) order point calculation

Know the normal distribution of general statistical properties and has worked out the predicting error of the standard deviation or average absolute deviation MAD, order point calculation is very simple. This chapter discussed before ahead of expected in the above requirements and a standard deviation is 84% of the services are as the goal, plus two standard deviation will service level increased from 98% to. The service level directly as a backup or safety stock with the standard deviation of several relevant; The number usually called safety factor.

Figure 5-7 is normal distribution under different service level of safety factor table, safety factor can be used standard deviation number or MAD several said. Because MAD is always less than standard deviation, so the use of the MAD to total number than the standard deviation of a number of more. For example the service level for 84.13%, safety stock to use 1 standard deviation or 1.25 MAD.

This form can be used to the calculation of service level of safety stock. For example hypothesis of data items X as follows:

Weekly forecast = 500 pieces

The lead time = 1 week

MAD = 200 pieces

Hope service = 98%

Order = 500 pieces

Because of the items weekly demand is 500, and the lead time is a week, is the lead time demand is the 500. MAD is 200 units. If hope to achieve 98% of the service level, figure 5 to 7 points out that the safety factor should be 2.56 a MAD.

So backup inventory = safety factor × MAD

= 2.56 x 200 = 512 pieces

And order point = the lead time demand in the + backup inventory

= 500 + 512 = 1012 pieces

This order point (according to the table) should be given 98% of the service level ─ ─ but in the calculation of "service" mean??????? It means in the replenishment during what percentage of the time demand should not be more than order point quantity. Order point is design to cover the lead time demand in the researched, and the material of a replenishment orders can be to give timely make the material in all inventory is withdrawn before the delivery to the store. The replenishment lead times is the end of a items can use up to the key moment of the stock. A shortage of items may "exposure" frequency is equal to the number of orders issued replenishment, of course, it depends on the size of the order. Large quantity of goods will require less every year financial replenishment, and more frequently than order of things to be less exposure to out of stock.

Order and security of the relationship between stock can be determined through the first will occur during the replenishment number (exposure to the number of times out of stock), and then the calculation to don't want to happen, out of stock replenishment of the number of said during the service level of the want to consider.

(6) prediction interval and the lead time difference of adjustment

(7) poisson distribution of mulberry use

(8) service concept

(9) the value of statistics

Principle 18. Experience with the law to set the backup inventory can't, because these rules ignore the need of their reason.

To remember the ABC classification inventory. High prices by most of the articles shall be close attention.

In most enterprise in one of the characteristics of demand is a more active items with a steady demand, and less active items have and fluid demand.

(10) use the matters needing attention

Unless a basic techniques that people understand, or it will not be successful application. All kinds of order point mutations are techniques that:

1, use will be continuous and hope that happened before in stock replenishment immediately

2, in order to uniform rate is actually use

3, advance the time of delivery is allowed but delay in delivery is not allowed and therefore should as far as possible to avoid

4, safety stock will be out of stock to provide adequate protection

5, capacity and material will be enough to deal with already issued the order

(11) regular evaluation techniques

Regular review techniques are often referred to as fixed cycle techniques. This method, the inventory records are regularly review and when each evaluation for each item for the replenishment of the order. Evaluation period is 1 week, 2 weeks or a month, it depends. The order, the inventory increase to make the existing order has a total amount or a predetermined target levels.

In the traditional method of order, each a login to review a inventory records, when existing with the balance of the order quantity has reached a predetermined order point when they deal with a replenishment of the order. In order of collocation, quantity is fixed, is usually EOQ.

Regular review of using the method of occasions is:

1, many times from inventory to small goods, so that every time delivery is not actual record all login. Food supermarkets, automobile parts supply store and the like the retail industry is an this type, such as electronic and mechanical machine parts business in manufacturing services.

2, ordering cost is small. This happened in from a source received many different items or write the order from a center to a warehouse warehouse inventory items transfer many branch of the order of the occasion.

3, in an order many items to form a production schedule is worth expected occasions, for example, can make this series of articles equipment adjust together or through a combination can order from a supplier get a discount or through the regular shipment and reduce freight wagon loaded with.

Target level is the sum of the following requirements:

1, the lead time demand forecast of DLT)

2, the evaluation period expected demand (DRP)

3, backup inventory (R)

One of the first and the third and order point elements are the same. Obviously, if two weeks no longer review inventory records, then in the period of the anticipated usage must be added to the lead time demand in the up, because only after the two weeks after the lead time can begin. Backup inventory available this chapter discussed above methods to calculate.

(12) two simple methods to place orders

For industrial inventory common in many low value items, often not worth using discussed above normal method. There are two commonly used methods can be used to control these no record low value items: two boxes of law and visual evaluation method.

Two cases of law: the equivalent to order point part of the inventory stored in the second box or containers quarantined, and then add seals. When the first box of all open inventory is used up, open the second box or backup containers and notify the materials control personnel order. This is low to keep a practical method of control items. The most commonly used in question is:

1, lack of adequate training and proper discipline, this system soon go bad. Don't understand this way of the reserve personnel will not notice the inventory with anyone, or supplementary materials and collect into not correctly to differentiate between open inventory and backup inventory.

2, once was determined, never to review the second box to put how many materials. As the item demand change, the number is no longer enough or be too big.

Two box method used in the best replenishment inventory maintenance and be controlled can entrust inventory in the room. Do this, this method is called bank inventory method. If the material in the workshop and let go of use, and it is hard to work.

Visual evaluation method: inventory was regularly check (maybe once a week or two every Monday time) and each item the order to a predetermined inventory level. These levels for a see be statements that the number of such as "a quarter box" and "six deep" as heavy order point and usually order quantity is big provisions. When the responsibility of keeping inventory to the individual person can't delegate, this technique is far better than two box method success. It use the site to adjacent workshop inventory is really good. In the lead time short and supplier to deliver goods to just drop at the end of the (arrears order) and so in addition to the last order without reserves outside of the material has the order before any record of the necessary occasions especially works. Of course, this is many retail stores ─ ─ especially big super market ─ ─ food by the main techniques. Using this method involves three main problems:

1, the necessary regular review inventory level of work didn't do

2, because the bad management, inventory is not on the right spot, PingShenZhe failed to find the actual all the stock on hand

3, no often check order goal, when demand change, make it become obsolete or useless.

If attention the following points, the only minimal record the value low items control method can get very successful use:

1, ABC inventory classification is the basis of high inventory levels, holding low items and sometimes minimal effort to control them. However, must remember, A line or packaging line can because of the lack of A C items (with A lack of A kind of item as) and shutdown. Don't forget to control the basic rules in low inventory is to have enough.

2 of high value, if more tight control inventory and can compensate for the low because of a loose stock control and increasing number of inventory, then this method does not benefit. The latter save time must be used to reduce the high value inventory.

3, visual control often used for loose control and sustainable records often used in tight control: but no one is must be so. Industry a common example is the aircraft industry rivets. Rivets unit price is low, but huge annual usage, so that they became A kind of item. Use visual techniques control such item can save many registration record time, but its inventory level can be controlled should be very tight.

4, low annual amount usage all things should be using visual review techniques to control as a general rule is not good. A in only one product use a component of each year whether to go every week visual check it? For this item should use material requirements planning.

Principle 19. Simple practical techniques may offer more economic inventory control.

(13) the order of period of time of the method

The traditional order point techniques have several main problems:

1, it put forward revision of the order by the lack of "need" date of ability.

In the current issue of 2, after an order, it does not provide will be issued the order of information in the future.

3, it is difficult to deal with the known particular time of the future needs.

4, it is difficult to deal with seasonal or cyclical demand.

5, it does not give advance warning will trigger the order.

The order point data in time section can overcome these difficulties and provide additional benefit. Items of the Z data are as follows:

Forecast = 20 pieces/week order = 100

The lead time = 2 weeks backup inventory = 55

The existing stock = 80 units already order = 2 weeks due 100 pieces

Order point O.P. = (2 x 20) + 55 = 95 pieces

To provide more useful graphics, this data can be shown in different period of 5 and 16. This show is the logic of purchasing and manufacturing of basic logic:

1, requirements? (prediction)

2, in stock? (existing quantity)

3, already order? (already order)

4, must be in when get more? (has plans to order to stage)

5, they must be in when to order? (has plans to order beginning date)