Engineering drawings and production drawings are different, and understanding the difference is important.

In larger electronics manufacturing companies

with specialized departments and mature

procedures there is typically a good understanding

of the difference between engineering drawings

and production drawings. In smaller companies,

however, this distinction can be lost and the wrong

sort of information can end up on the wrong

drawings. Or worse, the distinction between the

two sets of drawings can be lost as a company

struggles to manage with only one set.

This article clarifies the difference between the two

types of drawings, and shows how putting

information in the proper place brings benefits.

ENGINEERING DRAWINGS

For an electronic product, the Engineering

drawings define what the product should be.

The engineering drawing set is

produced by the Engineering

department, and is the final

output of the research, design

and development phase of a

project. The engineering drawing set includes

schematics, printed circuit board layouts, bills of

material, drawings for mechanical parts and

assembly drawings.

The engineering drawings set is a complete

specification of what the finished product is. Every

aspect of the product that is important to the form,

fit and function of the product is specified. Any

product, however manufactured, that is consistent

with the engineering drawing set is acceptable

PRODUCTION DRAWINGS

Production drawings show how to manufacture the

product.

In a medium or large sized organisation there will

typically be a production engineering department.

Production engineers take the engineering

drawings and decide how best to manufacture the

product described by the drawings in their factory.

They produce a set of production drawings that

detail the task to be performed, the equipment to

be used, the order tasks are to be performed in

and the procedures to be followed.

These drawings are used by the shop-floor

workers in their day-to-day activities. Machine

operatives, production line workers and

supervisors all use the production drawings as a

reference for how to go about manufacturing the

product.

For example, if the engineering

drawings called for a screw to be

tightened to a particular torque, the

production drawings would typically

detail which tool is to be used to

tighten the screw, and how it should be calibrated.

If the screw is in an awkward place the drawings

might also specify that this tightening is to be done

early in the assembly procedure, before access

becomes restricted.

DIFFERENT FACTORIES, DIFFERENT DRAWINGS

As such, the production drawings typically include

information that is specific to the particular factory.

One factory will have different tools and machines

than another and the production drawings will

reflect this. More dramatically, a factory located in

the first world will place a premium on labour and

will avoid labour intensive processes. A factory in

the developing world might choose very different

assembly methods, preferring labour intensive