Rugby School Thailand Design & Technology Senior School

1.6.2 Production systems

The use of computer systems

Computer systems for planning and control

Computers have revolutionised the way that products can be made, ranging from robotic production lines to home 3D printing. In industry, sophisticated planning and control software uses mathematical calculations to plan the schedules necessary to organise a complex manufacturing facility such as a car plant. Barcodes and Radio Frequency Identification (RFID) tags are used to facilitate the transfer of information relating to components and stock to and from computer systems.

Computer systems for manufacturing and production

Modular/cell production

Manufacturing cells are set up to combine a number of CNC machines in a group. This is known as a CNC module or cell.

The job of loading the material at the start of the process is often done by a robotic arm which can carry out a range of tasks. However, there are various types of robot that can be used in production.

robotics

1st generation responds to a pre set program and will carry on regardless of any external changes. If it were packing eggs and one broke it would carry on regardless. These are slowly becoming obsolete.

2nd generation robots are fitted with sensors which feedback information to a computer. The most common feedback method being used is a digital camera.

3rd generation use sophisticated sensors and AI. This type of robot is able to not only detect changes in the environment but also modify its working program.

beam transfer

Beam Transfer are relatively simple robots that operate on parallel slides or beams and are general used to pick up components. They can be seen in the car industry where they pick up body panels and move them along a manufacturing line.

arm robots

Arm robots are the most versatile and mimic the human arm. The

more directions they can move are know as ‘degrees of freedom’. The

‘hand’ part is known as the effector.

automatic guided vehicles (agv)

these are a little like fork lift trucks without a driver. They are robots used to carry components and items around the factory. They do this by using sensors hidden under the floor and reflectors on walls. They are often programmed to work with JIT systems so that they deliver materials to the right place at the right time.

Programming Methods

Robots can be programmed in three main ways:

Teach Pendant, similar to a remote control where the pendant is used to guide the robot through a series of moves. These are stored in the computer then converted into a control program.
Walkthrough where the robot is physically taken through the process while the computer records the movements before converting them into a control program.
Off-line is the most popular way to program robots. Virtual Reality simulations can be used to program the robot and test the program without any risk of damaging the robot or anything else in the work cell. They can also be used to rehearse dangerous operations such as maintenance in nuclear reactors.

Benefits of using Robots:

they carry out mundane tasks that humans find boring and repetitive and which would lead to making errors.
they can carry out physically demanding tasks which humans may not even be able to perform given their limited strength.
robots can work in hazardous areas where humans could be harmed or even killed. Bomb disposal is one such area or deep sea exploration.
they can work to high levels of accuracy, consistently and quickly whereas humans will make errors.
robots can work for long periods of time without the need to stop other than for routine maintenance. They need no food, water or breaks. This also means no human error, although there may be human error in programming or operating a robot.

Drawbacks of using Robots

robots still have poor mobility and flexibility compared to human workers who can move freely between cells and work on entirely different tasks without the need for reprogramming.
they have limited degrees of freedom compared to humans who are flexible and adapt their posture to work in tight or limited spaces.
set up costs for robotics are hugely expensive and even when installed they need programming and maintenance to ensure they are working effectively. If they cannot work for any reason, they are not easy to replace.
there are employment issues where robots are used to replace human workers. However, workers could be prepared to adapt to the use of new technologies by retraining for maintenance etc.

Quick response manufacturing (QRM)

Consumer needs change rapidly in todays market and that means industries can no longer manufacture items to go into stock or storage. Companies that do this run the risk of not being able to sell their stocks and have to clear out at a loss; often referred to as a ‘fire sale’. Instead, manufacturers often prefer to make to order. For example Jaguar and Land Rover both make cars that are already sold to customers so they are making to order. Of course this does mean a waiting list for the buyer but it means that no cars are sitting unsold taking up valuable space on a car lot which is good for the manufacturer. The use of QRM reduces the waiting time.

Manufacturers who mass produce items such as aerosols, toothpaste and so on will use dedicated equipment to produce only those items.

Investment in such products is relatively safe because demand for these items is high. In other markets items may have to be made in batches and in order to do this the equipment needs to be more flexible.

FLEXIBLE MANUFACTURING SYSTEMS (FMS)

Flexible manufacturing systems (FMS) can use machines which are

organized into cells. This is a temporary store used to hold partially

completed work as some machines work faster than others. A host

computer is used to sequence the jobs and monitor the status and

performance of each machine. Different products can be made in the

same cell at any one time.

The following equipment can be made to be more flexible:

Press Formers can use interchangeable dies depending on the job, but these can be very expensive so the range may be limited.
CNC Punches can be programmed to punch a variety of designs.
CNC Laser Cutters can be programmed to cut out a variety of shapes in a range of materials.
CNC Lathes and Milling Machines can be programmed to do highly accurate one off jobs or batches of identical items. Typically lathes are used to turn the diameter of bars, machine threads and face and drill ends.
Robot Arms can be programmed to do a range of jobs and can be fitted with tools for welding, spraying, lifting and so on.

Computer systems for production, distribution and storage

When manufacture is talking place, the stock of parts (inventory) can be monitored using a barcode or RFID tags, and JIT systems rely on them for an efficient flow of parts. Once made, the storage, distribution and sales can all be monitored by computer systems (see EPOS systems).

Computer Integrated Manufacture (CIM) brings the various elements of the design process together under computer control. It can also refer to the central computer and systems that organize scheduling and materials ordering etc.

Standardised components are those that are able to fit other elements of a design. Consider what would happen if you bought a plug only to find it didn’t fit the socket.

One significant breakthrough in standardisation was the British Standard Whitworth screw thread introduced in 1841. Before this there were many different types and sizes but there is now a metric International Standards Organisation (ISO) that has been adopted to ensure consistency across standardised components.

The USA and Canada still use a thread sizing system based on an inch but ISO metric threads are now becoming the standard.

Bought in components are used extensively where it would not be practicable or economical to manufacture those components in house.

A good example is computer processors (CPU’s) and RAM. Most high end manufacturer of products still buy these in from companies such as Samsung, Intel and AMD. However, because of their manufacturing facilities, Apple and Samsung now make their own CPU’s but still require parts bought in from other manufacturers. The same can be said for car and bike manufacturers. Even furniture manufacturers buy their fittings and accessories from 3rd party suppliers.

CHANGING STANDARDS

When standards change it can cause major problems. Smartphones currently use a variety of different connectors for charging which can be a real pain for consumers. A ruling in 2019 stated that all manufacturers must move to the USB-C connection standard but this will cause problems for companies such as Apple who have their own proprietary Thunderbolt/Lightning connectors.

When such standards come into effect consumers may find their existing docks, chargers and accessories become obsolete.

sub-assemblies

Sub-assemblies are elements of a product that are created as a unit prior to being combined into a final product. A good example is a bicycle which would incorporate several sub-assemblies such as:

gear cassette
braking system
lighting system
wheels
saddle
frame
chain

Most manufacturers concentrate on making their parts well and this is why bicycles, cars and motorbikes often have parts and sub-assemblies made by other manufacturers.

Summary

Scales of production range from one-off/bespoke to continuous production. The materials and processes used for each will be very different depending on the cost involved.
Modern manufacturing relies very much on the use of new materials and production techniques which take advantage of new technologies such as Virtual Reality and rapid prototyping technologies such as laser cutting and 3D printing.
Production lines need to be flexible in order to adapt to changing consumer needs but the machinery and materials used are dictated by the scales of production required. See QRM and FMS.
Expensive robotic production lines are not at all practical for one off or small batch production while continuous production cannot produce bespoke individual items expected by one off customers.
Manufacturing products can be improved by the use of computer aided engineering. See FEA and Topology in the next unit.

Revision notes

There are a lot of acronyms in this unit so ensure you are familiar with UPS, QRM, FMS etc.
You will likely be making a ‘one-off’ prototype as an outcome in your NEA studies but you really should be considering how it could go into production and be made in industry using batch or mass production techniques.
Ensure you know how computer systems are used in the planning, monitoring and production of products. This will be useful when studying the ‘cradle to grave’ life of a product in a later unit.
Become familiar with the CNC machinery in your centre as this will help to understand how products can be made quickly and accurately in larger numbers (batch and mass production).
When making your own products consider how you can reduce wastage and increase production time.

Exam question 25

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