Design For Manufacture (DFM)
Design for Manufacture is a
strategy to reduce the production cost and delivery time of a product, while
maintaining the quality level. Cost
management can be
most successfully implemented during the planning and design stage and not at
the manufacturing stage when the product design and processes have already been
determined and costs have been committed.
Figure 1, shows that product planning and
design cost expenditure must be about 20% of the total cost. Design
requirements of the product are defined in the design phase. While during the
planning phase, one of the factors is cost estimation / commitment for
prototype fabrication, prototype evaluation & qualification and prototype
acceptance review.
Usually in production industries there are
departments for the product process cycle. The role of Design and Development
department is to plan and design the desired product. Mechanical Production
department provides the product fabrication. Inspection department illustrates
the product evaluation and qualification and Quality Assurance department
checks the product acceptance review.
“Throw it over the
wall to be made” is business slang for completing your part of a project and
then passing it off to the next department. The phrase is usually said when
there is little communication between two departments.
In case, a product design
is completed in the design and development department. Foregoing, this
department should transfer the data to the mechanical production department for
the fabrication process. These procedures correlate with the term “throw it
over the wall to be made”.
General Principles of DFM
The general principles of Design for Manufacture are used to
assist the designer and manufacturer in order to reduce the cost and complexity
of fabricating an item. Following are the general rules:
Ø
Reduction of components
Reduction of components
in an assembly is probably the best approach to minimize the manufacturing
cost. Fewer parts involve less design time, machine time, assembly time,
inspection time, handling time etc.
Components of an assembly can
be reduced by implementing manufacturing processes that follow one component
output techniques, such as injection moulding, die casting, powder metallurgy
etc.
Ø
Use of standard components
Standard components are easily
available in the market and less expensive than the customized components.
Standard components are more reliable and make it convenient for the supplier
to meet the production schedules.
Ø
Design components to be multi-functional
Multi-functional components
reduce the production cost of components in an assembly. The designer needs to
identify the multi-functional components in the planning phase. In case, if a
component has the capability of both electric and thermal conductivity then there
is no need to place two components separately for electric and thermal
conductivity in an assembly.
Ø
Design parts to be multi-use
Multi-use components eliminate
the duplication of components in an assembly line. This principle will be
useful in planning phase, if the designer has the list of all the components in
the firm that can be used for multi-use applications.
Ø
Design for ease of fabrication
The designer and manufacturer
should select the optimum material and manufacturing processes in order to
minimize the manufacturing cost. Too much tolerances and high surface finish
requirements usually increases the unnecessary production cost.
Ø
Minimize assembly directions
It is better to assemble all
the components in one direction in an assembly line. Gravitational effects in
the vertical direction components help the assembly process.
Ø
Maximize compliance
It is necessary for a
designer to include compliance in the component design phase in order to avoid
errors in the insertion procedures.
The variations in the component
dimensions and position accuracy can cause damage to the assembly of the
components.
Importance of DFM
Design for Manufacture is an approach which has the aim of improving
manufacturing productivity and bringing benefits to the industries by
minimizing errors and incorporating precaution measures. It helps the
industries to focus on clear and common objectives, eliminate the problematic areas
and design a product using top-down approach. Design for manufacture is an
important factor in production industries and can lead to a 25-30% reduction in
production cost without capital investment in new facilities.
