Pertemuan 6 : Penentuan Tingkat Persedian (lanjutan)

Summary

This lecture on inventory planning and control delves into methods for determining optimal inventory levels using the Economic Order Quantity (EOQ) model. It covers fundamental concepts such as push inventory control, basic order quantity systems, and the impact of ordering and storage costs on inventory management. The script highlights how EOQ minimizes total inventory costs by balancing ordering and holding expenses. Additionally, it explores the effect of production rates on inventory and introduces concepts like Economic Manufacturing Quantity (EMQ). Practical examples and formulas demonstrate how to calculate optimal order sizes and costs in real-world scenarios.

Takeaways

• 😀 The lecture focuses on inventory planning and control, specifically methods like Economic Order Quantity (EOQ) and Economic Manufacturing Quantity (EMQ).
• 😀 EOQ aims to minimize the total cost of inventory by balancing ordering costs and holding costs.
• 😀 The key assumption in EOQ is that demand is constant, lead time is fixed, and there are no stockouts allowed.
• 😀 The EOQ formula is derived by considering the trade-off between ordering costs and holding costs, with the goal of finding the optimal order quantity.
• 😀 The total cost for EOQ includes ordering costs, holding costs, and purchasing costs, and is minimized when these costs are balanced.
• 😀 As order quantity increases, ordering costs decrease per unit, but holding costs increase, leading to an optimal order quantity where total costs are minimized.
• 😀 The relationship between ordering cost, holding cost, and total cost is visualized in a graph, with the total cost curve reaching its minimum at the optimal order quantity.
• 😀 Economic Manufacturing Quantity (EMQ) adjusts the EOQ model for production environments, where goods are produced in batches rather than ordered directly.
• 😀 The EMQ formula takes into account the setup costs for production and the production rate, aiming to minimize costs while meeting demand.
• 😀 The lecture concludes with a discussion on reorder points, safety stock, and the use of advanced inventory systems like the P-system and Q-system to handle uncertainties in demand and supply.

Q & A

What is Economic Order Quantity (EOQ)?

Economic Order Quantity (EOQ) is a formula used in inventory management to determine the optimal order quantity that minimizes the total costs of inventory, including ordering costs and holding costs. The goal is to balance these costs to find the most cost-effective order size.

What are the main assumptions used in the EOQ model?

The EOQ model assumes that demand is constant and known, lead time for receiving orders is fixed, there are no stockouts allowed, and order quantities directly impact the total cost, which is made up of ordering and holding costs.

How does the order quantity affect the total inventory cost in the EOQ model?

In the EOQ model, as the order quantity increases, the holding cost rises because more units are stored. However, the ordering cost decreases because fewer orders are placed. The total cost is minimized when the sum of ordering and holding costs is at its lowest.

What is the formula for calculating EOQ?

The formula for EOQ is: EOQ = √(2DS/H), where D is annual demand, S is the ordering cost per order, and H is the holding cost per unit per year.

What is the significance of the 'total cost' graph in EOQ?

The total cost graph in EOQ shows the relationship between the order quantity and total inventory costs. It helps to identify the optimal order quantity, where the combined costs of ordering and holding are minimized.

What does the term 'Economic Manufacturing Quantity (EMQ)' refer to?

Economic Manufacturing Quantity (EMQ) is a variation of EOQ used when goods are produced in batches rather than being purchased from suppliers. It considers production rates and demand rates to find the optimal batch size that minimizes total costs.

How is the Economic Manufacturing Quantity (EMQ) calculated?

EMQ is calculated using the formula: EMQ = √(2DS/H) × (P / (P - d)), where P is the production rate and d is the demand rate.

What is safety stock and why is it important in inventory management?

Safety stock is the extra inventory held to prevent stockouts due to demand fluctuations or delays in supply. It acts as a buffer to ensure that inventory levels remain sufficient even in the face of uncertainties.

How do reorder points relate to safety stock?

A reorder point is the inventory level at which a new order is placed. Safety stock is factored into this calculation to account for uncertainties in demand or lead time, ensuring that orders are placed in time to prevent stockouts.

What is the difference between EOQ and the KI system?

EOQ assumes fixed demand and lead times, whereas the KI system incorporates variability in demand and lead time. The KI system uses reorder points and safety stock to adjust to these uncertainties and maintain continuous supply.