Fixed Automation (Hard Automation)
Fixed automation refers to the use of special purpose equipment to automate a fixed sequence of processing or assembly operations. It is typically associated with high production rates and it is relatively difficult to accommodate changes in the product design. This is also called hard automation. For example, GE manufactures approximately 2 billion light bulbs per year and uses fairly specialized, high-speed automation equipment. Fixed automation makes sense only when product designs are stable and product life cycles are long. Machines used in hard-automation applications are usually built on the building block, or modular principle. They are generally called transfer machines, and consist of the following two major components: powerhead production units and transfer mechanisms.
Advantages
■ Maximum efficiency.
■ Low unit cost.
■ Automated material handling —fast and efficient movement of parts.
■ Very little waste in production.
Disadvantages
■ Large initial investment.
■ Inflexible in accommodating product variety.
Programmable Automation
In programmable automation, the equipment is designed to accommodate a specific class of product changes and the processing or assembly operations can be changed by modifying the control program. It is particularly suited to “batch production,” or the manufacture of a product in medium lot sizes (generally at regular intervals). The example of this kind of automation is the CNC lathe that produces a specific product in a certain product class according to the “input program.” In programmable automation, reconfiguring the system for a new product is time consuming because it involves reprogramming and set up for the machines, and new fixtures and tools. Examples include numerically controlled machines, industrial robots, etc.
Advantages
■ Flexibility to deal with variations and changes in product.
■ Low unit cost for large batches.
Disadvantages
■ New product requires long set up time.
■ High unit cost relative to fixed automation.
Flexible Automation (Soft Automation)
In flexible automation, the equipment is designed to manufacture a variety of products or parts and very little time is spent on changing from one product to another. Thus, a flexible manufacturing system can be used to manufacture various combinations of products according to any specified schedule. With a flexible automation system, it is possible to quickly incorporate changes in the product (which may be redesigned in reaction to changing market conditions and to consumer feedback) or to quickly introduce a new product line. For example, Honda is widely credited with using flexible automation technology to introduce 113 changes to its line of motorcycle products in the 1970s. Flexible automation gives the manufacturer the ability to produce multiple products cheaply in combination than separately.
Advantages
■ Flexibility to deal with product design variations.
■ Customized products.
Disadvantages
■ Large initial investment.
■ High unit cost relative to fixed or programmable automation.