Even with CAD technology, there are no good designs. There are only bad designs, and a sheet metal fabricator has to select the best out of all the bad designs to fabricate sheet metal components with an expectation to optimize costs.
Bad designs are a consequence of lacking synchronization between 2D CAD drafting and 3D CAD modeling with fabrication shop floor conditions. Fabricators wish that the design engineers would optimize the products design features to reduce production cost, while design engineers are keen on optimizing component’s performance.
Bad CAD designs are proof that there is a need of enhanced communication between fabrication shop floor and CAD jockey. All sheet metal fabricators wish that their design engineers would get constructive feedback or a shop floor tours to improve upon the bad designs.
Unleashing the trade secrets of sheet metal fabrication to sheet metal design engineer, working in a typical CAD station, and aloof from fabrication shop floor is one of the epic challenges. This is the reason why fabricators are availed with bad designs.
Although sheet metal design engineers employ Design for Manufacturing (DFM) strategy while designing, and keep the designs aligned with fabrication, there are instances when bad designs emerge from shop floor.
Regardless of DFM offering a comprehensive understanding for ‘how easy it is to fabricate a part?’ some designs are easy to develop than others. This is because, beyond skills and knowledge, sheet metal fabrication trade is a combination of material properties, tools and machines. The right question to ask should rather be, ‘Do the fabricators have appropriate tools and machines for fabrication?’
A CAD Design Workflow for Fabrication
As long as the goal of design engineer is only to please the fabricator, what you model is more important than how you model. However; when times are changing to efficient fabrication and costs are to be optimized, CAD platforms like SolidWorks dedicated to sheet metal are leveraged to help maintain the design consistency.
Product Manufacturing Information (PMI) and nesting drawings empowers sheet metal design engineers with viable options for fabrication.
Educating Product Design Engineers on Fabrication Terms
Along with right CAD systems and workstations, if the design engineers know the difference between various terms in fabrication, they can make better design decisions. These crucial design decisions significantly impact the fabrication method expenses.
Consider a segment of a factory producing goods through an automated gated entry of the assembly line. There are rarely any changes in such a large factory set up, producing end goods of similar shape and size. On the other hand, production line with job shop setting, changes in tooling are required with each new fabrication job. It is a kind of production line that is required to undergo small variations frequently.
For both the aforementioned examples, the fabrication methods and surface finish of end products are largely dependent on the 3D CAD models. Prediction of production costs about material planning and order quantity will largely depend on them. Thus, it is crucial for CAD design engineer to know the approach through which the part shall be fabricated along with its usability.
Alongside the size of fabrication output, the thickness of part to be fabricated is crucial. In a CAD design environment, the tools may work for any thickness and for any material, be it as soft as plastic or as tough as a metal; whereas on a fabrication shop floor, even 0.2 inches difference in thickness can make a huge impact.
Thus, all these factors, cumulatively, have a significant impact of final fabrication cost of any sheet metal component. Economic Order Quantity (EOQs) too are decided based on CAD files sent for fabrication purposes. It is thus a fabricator’s first ever wish that their design engineers understand fabrication jargons first. This is required to ensure that the investments are made only on what is needed for fabrication and not on the mistakes in designs due to lack of knowledge of what happens out there in shop floor.
DFM tips – Can they be really helpful?
A goof-proof designs, a symmetric part about some axis, setting the design around the tool, optimizing the designs as per the shop floor arrangements, and constructive feedback from shop floor are some of the common tips that any CAD sheet metal design engineer will give away when asked for efficient CAD designs.
But hold your thoughts for a moment, aren’t these tips already the DFM guidelines, written in their most lucid form? So why aren’t we adopting them?
The case is we do already. The only drawback is that there is a gap in what design engineer knows about fabrication and how it actually happens. If the design engineer is educated enough with the terminologies that a fabricator uses, the designs can be essentially aligned with the shop floor needs, methods and product’s end demands.