Starting CAD Without Requirements

One of the most common product development mistakes is beginning CAD modelling before clearly defining product requirements.

When requirements are unclear, teams often face:

• Frequent design changes

• Scope creep

• Delayed development

• Increased engineering costs

• Repeated prototype iterations

Before CAD work begins, define product function, target users, operating conditions, manufacturing constraints, materials and performance expectations.

A clear requirement creates a strong foundation for the entire development process.

Ignoring Manufacturing Method

A product should be designed with its manufacturing process in mind.

Problems often occur when a design is created without considering how it will actually be produced.

Different manufacturing methods have different limitations and requirements, including:

• Injection moulding

• CNC machining

• Sheet metal fabrication

• Casting

• Welding

• 3D printing

Ignoring manufacturing requirements early can lead to costly redesigns later in the project.

Overcomplicating Parts

Complex parts generally cost more to manufacture.

Unnecessary features, difficult geometries and excessive customization can increase:

• Machining time

• Tooling complexity

• Manufacturing cost

• Inspection requirements

• Assembly difficulty

Where possible, designs should be simplified without compromising product performance.

Simple designs are often easier to manufacture, assemble and maintain.

Poor Tolerance Strategy

Many designers assume tighter tolerances automatically create a better product.

In reality, unnecessarily tight tolerances often increase manufacturing cost significantly.

Excessive tolerances can lead to:

• Higher machining costs

• Increased inspection requirements

• Supplier challenges

• Longer production times

Tolerances should be applied only where necessary to achieve the required product performance.

Missing Assembly Access

A product may look good in CAD while still being difficult to assemble.

Poor assembly access can create:

• Longer assembly times

• Higher labour costs

• Increased production errors

• Maintenance difficulties

During development, engineers should review:

• Tool access

• Fastener locations

• Assembly sequence

• Serviceability

Good assembly design helps reduce both manufacturing and maintenance costs.

No DFM Review

Skipping Design for Manufacturing (DFM) review is one of the most expensive mistakes in product development.

DFM reviews help identify:

• Manufacturing challenges

• Cost reduction opportunities

• Material issues

• Assembly problems

• Supplier concerns

A design that works in CAD may still be difficult or expensive to manufacture.

DFM helps identify these issues before production begins.

Weak Drawings

Manufacturing depends on clear documentation.

Incomplete or poorly prepared drawings often lead to:

• Supplier confusion

• Incorrect quotations

• Production delays

• Manufacturing errors

• Rework costs

Good drawings should clearly communicate dimensions, materials, tolerances, notes and assembly requirements.

Strong documentation improves communication across the entire supply chain.

No Prototype Feedback Loop

A prototype should not be viewed as the final step before production.

Prototype testing provides valuable information that should be used to improve the design.

Skipping this feedback loop can result in:

• Unresolved design flaws

• Assembly issues

• Performance problems

• Manufacturing challenges

Products become stronger when prototype results are used to refine the design before production.

Conclusion

Many manufacturing cost increases can be traced back to decisions made during product development.

Starting without requirements, ignoring manufacturing methods, overcomplicating designs, applying unnecessary tolerances and skipping DFM reviews all create avoidable costs.

A structured engineering process helps identify problems early, improve manufacturability and reduce risk before production begins.

Investing time in proper product development often costs far less than fixing problems after manufacturing has started.