New product designs often start with simple hand sketches that eventually lead to detailed 3D models, as well as full-on manufacturing drawings. This latter part of the process is sometimes neglected, and designers do not always give the drawings the attention to detail afforded to 3D models.
A 3D model is just a representation of the final product but usually contains no manufacturing information (though it can be useful to program CNC machines). A proper set of drawings, on the other hand, describe how to make the part, the materials to be used, necessary surface finishes, assembly steps, part quantities, and so much more.
Even in today’s age when paper seems a thing of the past, manufacturers universally require that a properly developed drawing package (in PDF form, perhaps) is provided.
A note on process: with modern design and engineering tools, a digital 3D model is first created of the entire product. Much of the actual design work and problem solving happens at this stage. From this model, individual part drawings are created, with the software “drawing” the 2D views from the model data to save time and ensure the 3D model and 2D drawings are always in sync. The tools we have access to today are great, but an experienced designer is still essential to show the parts in the correct way, calculate and clearly note tolerances, specify materials and finishes, process notes, and more.
Benefits of professional manufacturing drawings
A manufacturing drawing is a means of communication between the product owner and the manufacturer. As such, it needs to convey the design intent to the manufacturer in a manner that they can clearly understand.
Any critical information that is left out can result in manufacturers using their own standards or past experience to fill in the gaps. This is potentially a tricky situation, as a manufacturer does not always know the full scope of the design or how the part will interface with other parts or equipment.
A clear and professional technical drawing lists all the relevant manufacturing information so that there is no ambiguity. Detailed part drawings combined with a 3D overview provides the best of both worlds; enough detail to make the parts correctly, and some visual context to aid in understanding the bigger picture.
Reduced manufacturing time
Professional manufacturing drawings can dramatically reduce manufacturing time, and avoid time spent fixing mistakes.
If poor drawings are supplied to a manufacturer, they might need to generate their own shop drawings to allow their employees to create the parts. This will cause long delays, since the manufacturer must learn for themselves how everything fits together, and customers are likely to receive a long stream of questions during this process.
If the manufacturer does end up using the poor quality drawings, the situation is even worse - the parts and product will end up incomplete, with wrong sizes, finishes, fits, and other errors caused by improper drawings which can then take weeks or months to correct.
Each time a clarification is needed on a drawing, it results in both time and financial losses. Both the manufacturer and the customer will have to put activities on hold to clarify something that could have easily been included in the drawing.
Improved quality control
Quality control is critical to maintaining product conformity and consistency.
Manufacturing drawings are used in conjunction with inspection and test checklists to hold manufacturers accountable as well as to clearly communicate requirements. Any time a part requires a specific tolerance (such as when it must fit with other parts or equipment), it needs to be calculated correctly and listed clearly on the drawing. Once the manufacturer’s QC representative signs off on the part, they confirm that it meets the tolerances specified on the drawing.
Without proper tolerance information, a manufacturer might be forced to follow every dimension of a drawing as accurately as possible; they might assume these dimensions will be used as a gauge for whether to accept or reject parts. Or, they may assume critical dimensions are unimportant, leading to costly rework.
High precision dimensions are not always necessary, and a good designer will have calculated the most forgiving tolerance for a certain part or function to allow the fastest and cheapest manufacture. Unnecessary high precision dimensions (commonly added by default to save design time) add confusion and cost. This cost overrun is especially common in machined components — extreme precision adds significant time to machining operations which can quickly inflate prices.
It’s critical to get dimensions and tolerances right so that the manufacturer can optimize their time and provide quality control feedback. Other features, like material and finish notes, or process specific info like weld specifications or assembly instructions, are just as critical to include in the drawings so that the product can be reliably manufactured at scale and over time.
Ease of changing manufacturers
A professional manufacturing drawing should be universally understood by any manufacturer. This means that if a manufacturer produces subpar components, continually misses deadlines, or raises prices, the same drawings can be taken to another manufacturer and work can continue.
This is another reason not to leave the development of manufacturing drawings to the manufacturer; they can use their internally generated drawings as leverage during negotiations, charge excessive fees in exchange for the drawings, or even claim ownership of the design. This often locks customers in with manufacturers who can then dictate the terms of the relationship.
Product design updates
Once a new product has been prototyped, changes are inevitable, and its drawing set needs to be updated to capture any changes that may have been required for manufacturing or functionality.
Up to date drawings can also be important if redesigns are needed after in-field performance reviews.
And for the next version of the product, a proper drawing set will save time on unnecessary duplicate work.
A poor drawing set, lost digital information, or a designer you can’t reach can make it impossible to make changes to a product. Sometimes, recreating the entire drawing package is the only way to move forward. Investing in a professional set of drawings not only comes with an expert design in the first place, but can save a ton of time and expense in the long run.
Developing a good set of drawings isn’t the only step in product development, but it is an important one. An investment here will go a long way to protecting you from unmanageable lead times and massive rework expenses. If you need an experienced design team to get the job done right, reach out and see how Riganelli Design can help!