Design for manufacturability: what if we have talked about it before?

ottobre 28, 2026

How much would manufacturability design of mechanical components change if the customer and supplier discussed the design before freezing it, instead of waiting for a difficulty to emerge during production?

It's a question we asked ourselves recently, after an incident at GSI. The drawing arrives, we open it, analyze the dimensions and tolerances, study the production cycle, prepare tools and equipment. Then we begin machining the component.

So far, so good. However, some geometries can test even a carefully designed process. Machining efforts increase, clamping becomes critical, and equipment that seemed adequate on paper begins to show its limitations. At a certain point, in our case, the equipment resigned: without warning.

We stopped and reexamined the component. We identified two possible modifications: a different fillet radius and some surfaces that could be simplified. Naturally, we couldn't decide to modify the design on our own. So, we presented our proposals to the client's technical department, explaining the difficulties we could mitigate.

The answer came quickly: the modifications were acceptable and did not compromise the component's function. For one of the fittings, the customer even indicated that we could further increase the radius if it would help with the machining process.

Excellent: a concrete discussion, helpful people, and a shared solution. But this very experience has raised a question.

What if we have talked about it before?

Design for manufacturability : When does correct geometry become difficult to achieve?

A technical drawing describes the characteristics that a component must meet. Dimensions, tolerances, materials, treatments, finishes, and geometric requirements are the result of design choices that can meet specific functional needs. The problem is that a geometry that is correct from a design perspective isn't necessarily easy to produce.

A very small fitting may require a specific tool.
A hard-to-reach surface may require additional retouching.
A geometry that is not conducive to tightening may require dedicated equipment.
Particularly tight tolerances may require more demanding processes and controls.

All of this can be perfectly justified: if a feature is essential for the functioning of the component, we must respect it.

The point is another: are we always certain that all production difficulties derive from truly indispensable functional needs?

Or, in some areas of the component, is there a margin of choice that could be evaluated together?

This is precisely the area where design for manufacturability can offer a concrete contribution.

The customer's drawing is not a suggestion

Before continuing, I think it's important to clarify one thing: when we receive a drawing, our job is to produce the component according to the agreed-upon specifications. We can't decide that a tolerance is excessive just because it's difficult to meet. We can't modify a fitting because it makes a machining operation easier. And we can't simplify a geometry without knowing its function.

Behind a seemingly insignificant detail there may be loading conditions, interference problems, assembly requirements or results of previous validations.

Manufacturers don't necessarily know all this information. For this reason, in this case, we asked the client to evaluate and authorize the changes. A positive response doesn't mean the geometries were poorly designed.

It simply means that, once the production difficulties were shared , a possibility of choice emerged that we had not previously explored.

The problem wasn't the designer's or the manufacturer's expertise. It was the moment when the two skills met.

Why not talk about it before building the equipment?

Let's go back to the episode: when we met with the client, some of the work had already been done.

We had studied the cycle.
Prepared the equipment.
The machine is busy.
Production started.

The difficulty that arose forced us to interrupt the process, reexamine the component, and evaluate an alternative solution. We then had to manage the operational consequences of the change: a situation many manufacturing companies are familiar with.

It's not just the cost of the equipment to be fixed, it's the technical hours required to analyze the problem, the machine time already used , the new checks, any updates to programs and documentation, and the rescheduling of work. And, when necessary, the communication of a new delivery date. With all the peace of mind that normally accompanies such communications.

In hindsight, the question is inevitable: if we had discussed that connection before building the equipment, could we have avoided some of these activities ?

In our case, probably yes. And if we had addressed the issue before even freezing the drawing, the comparison would have been even simpler.

Design for manufacturability: what the designer knows and what the manufacturer knows

Whoever designs a component knows the system in which it will function : they know the dimensions, assembly conditions, loads, durability requirements, and relationships with other components. They know which features are essential and which can potentially be reconsidered.

Manufacturers possess a different kind of knowledge: they know what happens when the tool enters the material, they understand the cutting forces, they know which surfaces can be used to hold the piece, they understand the limitations of the equipment. They can evaluate the accessibility of the tools, the stability of the machining operations, and the consequences of certain geometries on dimensional inspection.

These are different skills, and therefore complementary. The designer may know that a particular fitting isn't functionally critical. The manufacturer may know that increasing it would allow for a more robust tool or a more stable machining strategy.

But if this information remains separate, neither party has all the information needed to evaluate the alternative. Technical collaboration creates value when it allows for the pooling of information that neither party possesses entirely on its own.

How much can a small detail change the process?

On the drawing, a geometric modification may seem marginal:

A slightly wider radius.
A more accessible drain.
A simplified surface.
A tolerance re-examined.

In the workshop, however, the consequences can be significant.

Consider an internal fillet: if the radius is very small, we may be forced to use a smaller tool, with possible limitations in rigidity and cutting conditions. A larger radius, when functionally permitted, can expand the range of tool choices and machining strategies.

Or consider a surface that requires a particular grip: an alternative geometry might allow for easier clamping or reduce the need to regrind the component.

In other cases, a difficult-to-access feature can also complicate inspection. Modifying the geometry could simplify not only production but also dimensional verification. Of course, this isn't automatic; each proposal must be analyzed considering the entire component, its functions, and the implications for other processes.

But the principle remains valid: a small change in the design can have a much larger effect on the production process.

Design for Manufacturing: It doesn't mean designing just for the machine

The concept of Design for Manufacturing, or DFM, stems from the need to consider manufacturability during product definition. This doesn't mean the design should be indiscriminately adapted to the supplier's preferences, nor does it mean that the most economical solution is automatically the best.

A component must first and foremost perform its function correctly. Producibility is one of the variables to consider, along with performance, quality, reliability, costs, and customer requirements.

The value of the comparison lies in seeking solutions that simultaneously meet these constraints. If a fitting must have a specific geometry for functional reasons, that geometry remains a requirement. If, however, the designer confirms that a range of functionally equivalent solutions exists, we can evaluate which is most favorable for production.

The difference is substantial: we're not asking for a lower technical level of the component. We're trying to avoid production complexities that don't add value to its function.

How much does a complexity that we could have avoided cost?

When we evaluate the cost of a component, we tend to focus on materials, manufacturing processes, treatments, and inspections. But a production difficulty can generate costs that aren't immediately visible in the unit price.

Every activity has a cost; some are unavoidable, others arise from problems we could have addressed earlier. It's not easy to assign a precise percentage to the avoidable complexity in mechanical manufacturing. It depends too much on the components, the processes, and the level of existing collaboration. What is certain, however, is how much work a single geometric detail can generate. And how much the process can change when that detail is reexamined with those who understand its function.

The question, therefore, is not just about the cost of a process: how much of the work we do to solve production problems could be avoided by intervening earlier in the component definition?

The supplier must also present technical proposals

Of course, we can't always expect the customer to ask for a comparison; we suppliers must also do our part. Saying that a geometry is difficult to implement is only useful up to a certain point: the designer needs to understand why .

Which process becomes critical?
Which tool has a limitation?
Which clamping condition creates instability ?
Which feature requires particularly complex control?
And above all: what alternative do we propose?

A useful proposal should describe the critical issue , indicate the suggested modification, and explain the production benefits it could offer. It should also clarify which aspects the designer must verify before accepting it. In our case, we submitted specific modifications to the fillet radius and some surfaces. The engineering department was able to evaluate them quickly because it had the necessary information to understand their purpose.

This is what we believe to be the right way to collaborate: don't simply pass a problem on to the customer. Present a possible solution and allow those familiar with the component's function to verify it.

Design for manufacturability : the right time is before freezing the design

Technical comparison is useful even when the design is already finalized: our case demonstrates this. But the sooner it occurs, the greater the choice. During the early design stages, a geometric modification can be evaluated alongside other alternatives. However, once the design has been released, the production cycle defined, and the equipment built, any change may require additional work.

This is why I believe supplier involvement should be considered, especially when the component is new or has particularly challenging geometries. It's not necessarily necessary to organize a complex process; sometimes, a shared technical review before final release can suffice.

A time when design, production and quality can discuss the most critical features.

We have the tools. Sometimes we're only half an hour away.

Today the distance between customer and supplier is a much smaller obstacle than it was in the past:

We can share 3D models.
View the same detail.
Annotate a geometry.
Compare alternatives.
Organize a remote technical meeting.

We can transmit a complex model from one company to another in seconds.

Finding half an hour to discuss it while there's still some scope for choice sometimes seems like the most difficult step. Perhaps it's mostly a matter of habit: the designer completes the drawing, the purchasing department sends it to the supplier, the supplier prepares the quote, and production begins.

Technical discussion occurs when a difficulty arises : it's an understandable process, but not always the most efficient. For some components, it might be useful to schedule a brief manufacturability review before geometry, price, and lead times are definitively established. Not for every detail and not to discuss every measurement, but at least for new components, critical machining operations, and geometries that require particularly demanding equipment or processes.

The technical maturity to do so exists, as do the sharing tools. The question is whether we are willing to change the way we organize work.

What if we have talked about it before?

In the case we've described, the client demonstrated great availability. But he left us with a question that we consider even more important than the result achieved: what would have happened if we had consulted before building the equipment?

Designing for manufacturability does not eliminate all difficulties, it does not make every requirement modifiable, and does not replace the designer's responsibility for defining the component's function. It can, however, allow customers and suppliers to recognize in advance the characteristics that generate production complexity without offering a corresponding functional advantage.

Sometimes small choices are enough, made together at the right time, to impact equipment, times, costs, and delivery reliability.

In your experience, does this comparison take place during the design process? And what results has it allowed you to achieve?

For more information on the production of gears and special mechanical components, or to evaluate the manufacturability of a new project together, contact GSI Ingranaggi.

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