Welcome to the World of Stock Control!

In this chapter, we are going to explore how businesses manage their "stuff"—whether that's flour for a bakery, screens for a smartphone factory, or shoes in a retail shop. Managing stock (also known as inventory) is a balancing act. If a business has too much, they waste money; if they have too little, they can't sell anything! Don't worry if this seems a bit technical at first—we'll break it down step-by-step using examples you see every day.

Quick Review: What is Stock?
Stock usually falls into three categories:
1. Raw Materials: Components waiting to be used (like wood for a table).
2. Work-in-Progress (WIP): Items currently being made (a table without legs).
3. Finished Goods: Products ready to be sold (the completed table).

1. The Basics of Stock Control

Stock control is the process of making sure that the right amount of stock is available at the right time to meet customer energy without costing the business too much money.

Key Terms You Need to Know

  • Buffer Stock: This is "safety stock." It is the minimum amount of stock a business keeps just in case there is a delay in delivery or an unexpected surge in demand. Think of it like the spare tire in a car.
  • Lead Time: This is the amount of time it takes between placing an order with a supplier and the stock actually arriving. If it takes 5 days for your pizza to arrive (hopefully not!), the lead time is 5 days.
  • Reorder Level: The specific level of stock at which a new order is triggered. When stock hits this number, the manager hits the "buy" button.
  • Reorder Quantity: The actual amount of stock ordered from the supplier.

Key Takeaway: Effective stock control ensures a business never runs out of products (avoiding stock-outs) while keeping costs low.

2. Understanding Stock Control Charts

A stock control chart (sometimes called a "saw-tooth diagram") helps managers visualize their stock levels over time. Imagine a graph where the vertical line (Y-axis) is the "Number of Items" and the horizontal line (X-axis) is "Time."

How to Interpret the Chart

  1. The Top Peak: This is the maximum stock level. This happens right after a delivery arrives.
  2. The Sloping Line: This shows stock being used up over time.
  3. The Reorder Level: A horizontal line mid-way up. When the sloping line hits this, a new order is placed.
  4. The Bottom Line (Buffer): The line never (ideally) goes to zero. It stops at the Buffer Stock level.

The "Magic" Formula:
You might be asked to calculate the Reorder Level. It looks like this:
\( \text{Reorder Level} = (\text{Daily Usage} \times \text{Lead Time}) + \text{Buffer Stock} \)

Example: If a cafe uses 10kg of coffee a day, the supplier takes 3 days to deliver (Lead Time), and they want to keep 5kg as a safety net (Buffer Stock):
\( (10 \times 3) + 5 = 35\text{kg} \).
When they have 35kg left, they must place a new order!

Quick Review Box:
- Lead Time: How long the supplier takes.
- Buffer Stock: Your safety net.
- Reorder Level: When to order more.

3. Methods of Stock Control

Businesses use different "styles" to manage their stock. Here are the main ones in your syllabus:

Just-In-Time (JIT)

JIT is a system where stock arrives exactly when it is needed for production. There is virtually no buffer stock.
Analogy: Instead of buying a week's worth of groceries, you buy the ingredients for dinner 10 minutes before you start cooking.

  • Pros: Reduces storage costs; stock doesn't go out of date.
  • Cons: Huge risk! If the delivery truck is late, production stops completely.

Kanban

This is a Japanese system (often used with JIT) that uses signals to restock. When a bin of parts is empty, a "Kanban card" is sent back to the supplier or the previous stage of the factory to say "We need more!"

Electronic Methods

Most modern shops use Electronic Point of Sale (EPOS). When the cashier scans a barcode, the computer automatically deducts that item from the inventory count. If the stock falls below the reorder level, the computer can even order more automatically!

Economic Order Quantity (EOQ)

This is a mathematical approach to find the "perfect" order size that minimizes the total cost of ordering and the cost of holding the stock.

Key Takeaway: JIT is great for saving space and money, but traditional "Just-in-Case" (holding buffer stock) is safer if suppliers are unreliable.

4. The Importance of Holding Stock (The "Why")

Holding stock isn't free! Managers have to weigh the costs against the benefits.

The Costs of Holding Too Much Stock (High Stock Levels)

  • Storage Costs: You have to pay for warehouses, heating, lighting, and security.
  • Opportunity Cost: Money tied up in stock could have been spent elsewhere (like on a new marketing campaign).
  • Spoilage/Obsolescence: Food goes bad, or tech (like smartphones) becomes "old" and unsellable.

The Costs of Holding Too Little Stock (Low Stock Levels)

  • Stock-outs: If a customer wants to buy and you don't have it, they will go to a competitor.
  • Production Halts: If a factory runs out of one tiny screw, the whole assembly line stops.
  • Higher Transport Costs: You might have to pay for emergency, expensive deliveries.

Did you know?
Amazon uses massive robots to manage their stock control. The robots bring the shelves to the humans, ensuring that the "Lead Time" inside the warehouse is as short as possible!

5. Stock Control and Production Methods

The way a business makes its products affects how it manages stock. Let's look at the link:

  • Job Production: (Making one unique item, like a wedding cake). Stock is usually ordered specifically for that one job. Low stock levels are kept.
  • Batch Production: (Making a group of similar items, like a batch of bread). Stock levels vary. You need enough flour for the whole batch, but then stock drops until the next batch.
  • Flow Production: (Constant mass production, like Coca-Cola). This requires a constant stream of stock. JIT is very common here because the volume of stock is so high that storing it would be too expensive.

Key Takeaway: The more "continuous" the production (like Flow), the more important precise stock control becomes to avoid expensive delays.

Final Check: Common Mistakes to Avoid

1. Confusing Lead Time with Reorder Level: Remember, Lead Time is time (days/weeks), while Reorder Level is a quantity (number of items).
2. Forgetting Buffer Stock: In exams, if a question asks why a business holds stock, always mention buffer stock as a safety net for unexpected demand.
3. Assuming JIT is always best: JIT is efficient, but for many small businesses, the risk of a supplier failing is too high. Always look at the context of the business in the case study!

You've reached the end of the Stock Control notes! You now understand how businesses manage their inventory to stay efficient and keep customers happy. Well done!