It is very important that manufactured products are produced to a high standard.
This the process of checking for quality during the overall manufacturing process. Quality means fitness for purpose and includes accuracy, surface finish, strength, reliability etc dependent on the product.
Inspection at every stage is needed starting with materials and components being delivered to the plant.
During production it is achieved in a range of ways - sensors may check temperature, colour, weight or thickness etc. during a continuous flow production, a sample can be taken every 100 or so units for testing during a mass production process. Sometimes a component must be tested to destruction e.g. testing the strength of a weld.
Testing of the finished product also takes place and will also include follow up with the customer after the sale.
This is the system of building the checks into the production system.
BSI - Kitemark
This symbol is a mark of quality. It is used on products that comply with the relevant British standards especially for safety.
This symbol which is widely used across the European Union means that the product meets the standards of quality and safety laid down by a European Directive.
This is the limits within which the product is made. Even though a production process produce identical products there will be slight variations. Testing as part of quality control checks to make sure that the variations fall within the tolerance. Tolerance is stated as + or - a percentage e.g. + or - 2%. The tolerance can apply to any characteristic of the product such as size, colour and weight.
Many of the tests are fully automated but some require skilled measurement by engineers.
CAM (computer aided manufacture)
When production lines are fully mechanised , they are automated and there will be no human operatives.This automation has been used in production for many years. Nowadays computer controlled machinery has also become common on production lines. Computer controlled machines include robots, CNC lathes and mills, laser cutters etc. Due to the way in which the computer controls the machine tasks can be completed which may be virtually impossible using older methods. Computer systems also monitor and check progress.
Scales of Production
One off (Job)
This is where a single product is made (or very few). Examples are craft items, jewellery, pottery, furniture, a display.
Expensive because all of the costs of design and manufacture must be recovered in the price charged. Skilled workers are needed. Expensive materials may be used. Production time is longer because everything is being marked out and made only once.
A batch of say 500 units are made. This means jigs and templates are used, specialist machines and equipment are used and the workers will have particular skills. Once the batch is produced another batch with changes may be made. Examples include clothes, personalised stationery, cakes, furniture such as stools or coffee tables. ( Where the batch is repeated regularly it sis known as repetitive batch)
Invented by Henry Ford. The product moves along a production line, workers move forward and complete a stage in the assembly or process, the product then moves onto the next set of workers for the next stage of manufacture. Expensive setup costs but lower costs per unit. The production lines can stop if there is a problem at any point. Workers can be trained very quickly to work on a production line.
Examples are cars and electrical goods.
Continuous Production (Flow production)
The product is produced in enormous numbers for a long time. The cost per unit is very small. Examples are screws, glass bottles, plastic tubes, petrol, glass, steel, etc. The whole process may be fully automated i.e. no workers!
Mass production is sometimes classified here as well.
Just In Time (JIT)
This is designed to reduce costs for the manufacturer especially by reducing storage costs. Components are delivered to the production line as they are needed. A problem if the delivery does not arrive. Car production makes good use of JIT, where each car made is to the customers' specification. The correct components arrive as the car reaches the correct stage on the production line. (a car may take two days to complete the journey around the plant).