Product Redesign - Update Design to Ideal Robustness I RD8

Product Redesign

INDEX 0

Product redesign: update design to a "0" score - the ideal robustness - to achieve a greener product and cost reduction on products

Redesigning a product to a robust design will result in a lot of benefits. For example, product redesigning will lead to a cost reduction on products. Besides that, you will also achieve benefits within sustainability, development times, and product performance with a robust design.

Sustainability

GREENER

Example...

CO2 emissions reduction
Complexity reduction

SIMPLER

Example...

Reduction of production scrap
Engineering Productivity

FASTER

Example...

Reduction of lead time
Product Performance

SMARTER

Example...

Improved product lifetime

The RD8 product redesign approach links to the unique metric, the RD8 Index, which quantifies the robustness of a given product. A low RD8 Index represents a robust design. A high RD8 Index represents a sensitive and/or complex product.

 

Product complexity and sensitivity are closely linked to product part cost, development, maintenance, and production efforts. A high RD8 Index reflects that too much information is tied up in the product – thus stating unneeded additional requirements. See the example at the bottom of the page where robust design eliminates +60% of the measure.

 

Product redesign aims to redesign the given product to realize identified potentials. This is primarily done by improving the product’s geometry to achieve a better RD8 Index score and enables harvesting of the downstream results. Improving the geometry goes hand in hand with the overall product architecture, material choices, part count, and standardization. The primary drivers for total production cost is dictated by the design arising from the development phase. Why not rethink and spend efforts on product improvements if the objective is cost reductions on products? Our advice: go to the root cause and redesign the product to achieve desired yields.

Interface

Robust redesign example - before and after

Below is a before and after example of two parts (grey and green) - shown in a section cut - to illustrate some mating features in the interfaces.

The interface score of the sensitive interface is 4, meaning 4 additional and unnecessary geometry features that add complexity to the product. A score of 0 is ideal since the interface is in equilibrium and has the exact amount of information/constraints that it needs.

This is one of many redesign disciplines.

Example

Simplification: Product redesigning equals complexity reduction and cost reduction on products

To say it in a simple way: Product redesigning will lead to a complexity reduction, which equals cost reduction on products.

Changing part production from one production process to another can reduce part cost, improve product performance, and reduce CO2 emissions.

 

Changing from one process to another often requires a lot of important considerations, including tolerances. This is because production processes have different production capabilities. The chart below shows International Tolerance Grade ranges for various production processes. A higher grade equals wider and more course tolerances.

View of IT-grades and production processes

For example, going from reaming (IT6 to IT10) to drilling (IT10 to IT14) will result in expected wider tolerances and faster machining cost; hence lower part cost. The cost index between a reaming tool and a drilling tool is also in magnitude of factor 10.

Robust design of components can enable more course production processes that are often cheaper and more energy/CO2 efficient.

Simpler

Example: +60% reduction of part requirements by robust design in an interface between two parts

Most interfaces in a mechanical product are not optimized to a low RD8 Index score. The result hereof is that one will need to over-specify the components to handle the complexity. This often reflects in additional measures on a part and/or 2D drawing. The example below will illustrate and indicate the needed measures on a "standard design" and a "robust design" and highlight the difference between them. It is seen that a +60% reduction in the number of measures in this simple example.

The example above shows a “standard design” and an “optimized robust solution”. Linear and geometrical tolerances are indicated on illustrations (in practice, the measures should be shown on both parts – through the percent-wise evaluation will be the same.

Standard design

  • Three measures in the x-direction
  • One measure in the y-direction
  • Requirements to parallelism for the two ribs and their counterfits
  • Position requirements ribs placement relative to “x1” and “x2” features
  • Straightness requirements to ribs and counterparts

Optimized Robust Solution

  • Two measures in the x-direction
  • One measure in the y-direction
  • Requirements to parallelism for the two ribs and their counterfits
  • Position requirements ribs placement relative to “x1” and “x2” features
  • Straightness requirements to ribs and counterparts

Reduction of measures is a crucial driver for wider tolerances and enables changing the production process to less costly processes, and reduces the requirements for expensive QA.

The downstream effects of less complexity is a true driver for cost reductions on total cost of product with effects on development time, testing, sourcing, production, assembly & inspection.

This example is very simple - thus the effect is quite significant. There are much more potential in many industrial applications out there!

Robustness Philosophy

Axiomatic design & classic robust design on top of a foundation of kinematic design.

Design for sensitivity, complexity reduction and decoupling – based on a kinematic design foundation.

RD8 Robust Design Philosophy