by Alex Krulikowski

Standard-compliant drawings are the minimum level required to provide a clear definition of part tolerances. This post explains what is a standard-compliant drawing and discusses three-levels of dimensioning of drawings.

Time is money.

The truth of this old maxim is evident in the world of manufacturing, where:

Poor drawings = wasted time = higher costs = lower return on investment

However, companies can reduce product development time and product costs by using GD&T to define parts clearly, completely, consistently, and with the maximum tolerances allowed by the part function. When drawings are made to standard compliance, the formula changes:

Standard-compliant drawings = reduced production time = lower costs = higher return on investment

Simply put, many of the problems in industry stem from poor or nonstandard-compliant engineering drawings. Using drawings that aren’t standard compliant results in:

  • Disputes with suppliers
  • Problems during inspection
  • Functional problems

These issues add up to unnecessary production time and costs. In my experience, over 50% of the drawings in industry are not standard compliant.

I categorize the dimensioning of drawings into three levels: a standard-compliant drawing, mixed-method design, and functional design with analysis.

Level I: A Standard-Compliant Drawing – A standard compliant level drawing follows the GD&T Y14.5 Standard, provides clear definition of part tolerances, and enables outsourcing repeatable part inspection. Standard-compliant drawings are the MINIMUM level for communicating part requirements.

Level II: Mixed Method Design – A mixed method design level drawing includes all the characteristics of a standard-compliant design, plus starts to address dimensioning style and tolerance values.

Level III: Functional Design with Analysis – A functional design with analysis level drawing includes all of the characteristics of standard compliant design. It also places the focus on functional dimensioning and uses tolerance analysis to ensure that tolerances are in line with the product function derived from customer requirements.

The chart below shows the potential benefits from creating drawings at each level.

Benefits_of_Drawing_Chart_8-15-17

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Creating drawings at the functional design with analysis level can provide significant return on investment and is the strategic goal for many organizations. However, this level takes the most effort to achieve and cannot be accomplished without consistent management involvement — a topic that is too lengthy to cover in detail here.

I believe that there are many benefits to be realized by first bringing the drawing quality level to standard-compliant, and then working towards making drawings using functional design with analysis. For now, let’s move on to look at some dimensioning guidelines for each of these levels.

The next chart illustrates the dimensioning guidelines that I use as the benchmark for each drawing level in a drawing audit, or for customer mentoring.

eti_dimensioning_guidelines_8-15-17

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The next chart summarizes the advantages and disadvantages of achieving each drawing level.

eti_advantages_of_Drawing_Levels_8-15-17

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Conclusions
Many executives and managers want their employees to create drawings at the Functional Design level. But most companies are not up to the Standard Compliant level. Significant gains can be made simply by achieving the Standard Compliant level. The road to creating quality drawings is not easy, but it leads to many important advantages for the organization.

Six steps to improving drawing quality:

  1. Develop awareness of the various dimensioning levels, benefits, and requirements in the organization
  2. Obtain an agreement from key stakeholders on where your organization’s drawings need to be
  3. Conduct a drawing audit to find out where your organization’s drawings currently stand
  4. Create a strategy to move to the desired level
  5. Create a set of SMART goals and an action plan to support the strategy

Incorporate steps in your product development process to ensure that the drawing level is maintained.

Are your drawings standard complaint?