ÜRETİM YÖNETİMİ

Lot size refers to the quantity of an item ordered for delivery on a specific date or manufactured in a single production run.

Continuous review system refers to a process designed to track the remaining inventory of an item each time when a withdrawal is made to determine whether it is time to reorder.

In periodic review system, the inventory level is controlled at the beginning or end of predetermined time intervals.

Visual control, is a simple and practical method that is widely used in small businesses or markets. In this method, inventory levels are periodically reviewed by an experienced warehouse officer. Order items that fall below a certain level are immediately ordered. The level of order and the order quantity are entirely left to the official’s experience.

Material Requirement Planning (MRP) is a system that regulates production plans for final product’s production decisions, control of inventory levels of raw materials and parts, and programs of workshop and assembly unit. MRP is a method that tries to find the most economical answer to the questions of “when to order” and “how much to order” for dependent inventory items.

Aspects of material requirement planing are as follows:

The three important factors for successful implementation of the MRP system are:

Inventory holding cost (H): Costs are arising due to inventory holding. Inventory holding cost is the sum of the cost of capital plus the variable costs of keeping items on hand, such as storage and handling costs and taxes, insurance, and shrinkage costs. When these components change with inventory levels, so does the holding cost.

Following are the underlying assumptions for the EOQ model. • The demand rate for the product (D) is constant and uniform throughout the entire planning horizon. • The order quantity (Q) is constant. • The demand rate for the year is known and evenly spread throughout the year. The product price is constant for the entire planning period. • The lead time is not fluctuating. • The average inventory level is taken into account when calculating the cost of holding. • The cost of ordering is constant and independent from order quantity. • All the demand in the planning period must be met. • All orders are delivered simultaneously.

Pareto principle can be interpreted as that a minority of inputs (around 20 percent of the input) results in the majority of outputs (around 80 percent of the output).

Inventory management refers to the process of ordering, storing, and using a company’s inventory.

The purpose of inventory control is to ensure that the material requirements are met at the “desired time”, at the “desired quantity”, at the “desired location” and at the “desired quality”. In order to achieve this goal, it is necessary to determine “which materials” are to be stocked and to decide “what amount of inventory” is to be kept.

Continuous Review System: A system designed to track the remaining inventory of an item each time when a withdrawal is made to determine whether it is time to reorder.

Visual control is the review of inventory levels by the experienced worker individually on the place of the inventory.

The MRP system contributes to the provision of effective inventory management at the following points:
• Inventory investments are kept in a minimum level.
• The MRP system is sensitive to changes.
• MRP creates a forward-looking perspective based on inventory items.
• Order quantities are determined according to the requirements.
• It focuses on the timing and complete fulfillment of requirements.

The seven wastes that causes the costs to increase were determined by Toyota, the developer of the lean production system, as follows:
1. Overproduction
2. Transport
3. Inventory
4. Motion
5. Defects
6. Over-processing
7. Waiting

Lean Enterprise Institute (LEI) (http://www.lean.org/), is a nonprofit publication-training and research organization founded in the United States in 1997 to promote a broad range of lean thinking principles from production to service sectors and in all aspects of business.

The variables used in the EOQ model are as follows:
D = Annual demand (unit/year)
C = Purchasing price per unit (T/unit)
A = Ordering cost per batch (T/batch)
i = Annual interest rate (%)
H = Annual cost of holding per unit (T/unit-year)
Q = Order quantity (unit)

Also known as RFID, such systems make inventory control very easy. Both RFID technology and barcode technology involve the
scanning of products in order to enter them into the system. The main difference between the two is that barcode systems use barcodes printed on pieces of paper, which are then stuck on the products, while RFID uses small microchips that are either placed on a tag attached to the product or on the packaging of the product itself.
Another major difference is the bandwidth of the two technologies. A barcode scanner needs to scan each unit individually for it to be entered into the system. An RFID reception device, on the other hand, will pick up on the signals coming from all of the microchips within a given radius. With RFID technology, the task of controlling inventory is made much easier and faster.

A large part of this cost arises from cost of investment tied to the inventory. This cost can be considered as the cost of opportunity loss which is the result of the deprivation of loan interest or other investments that could have been done with this money.