Opportunities for Disruption: CAD/CAM Workflow for Apparel Design

At every moment, you are surrounded by objects.  How were those objects made?  Most of the rigid world built today is fabricated with the direct assistance of Computer Aided Design (CAD) and Computer Aided Machining (CAM) tools.  This is also true for the design and manufacturing of garments, but the processes are markedly different.

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CAD/CAM for Rigid Objects

The computerized processes for rigid objects can be generally categorized in two methods: additive manufacturing and subtractive manufacturing.

Additive Manufacturing – is synonymous with 3D printing.  Materials are added to create a shape.  While usually it isn’t referred to as additive manufacturing, in fully fashioned knitting, yarn is specifically added to create the desired shape.  This type of knitting is a kind of additive manufacturing processes.

Subtractive Manufacturing – refers to machining, milling, and any other processes that take material away from a larger piece of source material to create the final shape.  

Another method of subtractive manufacturing involves only 2D tools.  This includes laser cutting, water jetting, and other forms of CNC cutting.  It is the same process in cut-and-sew.  Fabrics are created in larger pieces and then the materials that are not part of the final garment are cut and removed.

Read more about the differences between Additive and Subtractive manufacturing here.

CAD/CAM Workflow for Rigid Objects

CAD and CAM tools for rigid objects are based on using computerized information to create physical objects in the real world.  A user can create a model (a 3D representation of an object) on their computer, say a cube.  The user can then use that model to create drawings with technical specifications.  They can also use the model to create tool paths to make the cube out of a physical material.  That model could be 3D printed, machined, or simply sent as instructions for someone else to manually create it.

Tool paths– refer to CAM processing.  These paths tell the machine where to add or subtract materials.

The high-level workflow for these files can be summarized relatively simply:

CAD files → CAM output → Assembly (if necessary)

Any revisions that take place in the original CAD file effect the CAM files made from it, and drawings associated with it.

CAD/CAM Workflow for Fabric-based Goods

Fabric-based goods, specifically clothing, are designed and developed with several more steps.  In general, there are very few full-garments that are made through an automated CAM process.  Also, multiple versions of CAD files are made as instructions.  The workflow for CAD/CAM for cut-and-sew garments is something like this:

A Designer uses illustrator to create CAD drawings for a tech pack  → CAD drawings are interpreted by a Patternmaker who makes a completely different kind of CAD drawing called a Pattern → Patterns are cut or plotted using some kind CAM system, either a cutter or a plotter → Samples are sewn into physical garments using the original CAD drawings as instructions 

CAD 1 design drawing

CAD 1 design drawing

CAD 2 pattern making file

CAD 2 pattern making file

Simplified, we can see what’s happening with the CAD/CAM files in this Process:

CAD 1 file → CAD 1 file manually converted to CAD 2 file → CAM output → Manual processes based on CAD 1 file

(Note: This does not include additional CAD/CAM processes for automated operations in mass manufacturing environments.)

Any revisions in this process are cycled back through from the start, in the original CAD 1 files.  The biggest challenge with a process as complicated as this one is that a lot can go wrong.  Problems in pattern making might have to be resolved in the original CAD 1 files because they are used as instructions later during manual fabrication of the garment.  The CAD 1 files and CAD 2 files have no inter-dependencies (meaning if you change one, it does not automatically effect the other.)  The CAD 1 files are purely instructional despite the fact that many of the physical shapes drawn within the CAD 1 file are related to the CAD 2 pattern file.


Why is it done this way?

The Role of the Fashion Designer

Fashion Designers often serve as translators between the business front end and the technical backend.  The business front end includes Creative direction, Marketing, and Sales.  The front end will give valuable insights into customer needs and desires.  On the back end, in order to make those products, strong technical skills are necessary.  Designers often manage that process.  This includes tech packing, pattern making, textiles development, maintaining contact with factories, and anything else involved in the Product Management Lifecycle (PLM).  At many companies, fashion design is more about filling in PLM spreadsheets and tracking development than it is about the design itself.

Before there were ever fashion design jobs, there were only merchandisers.  As manufacturers became more flexible in what they could and would make, merchandisers had more of a hand in designing the details.  As time went on, that job naturally split into two jobs, merchandising and fashion design.

The Fashion Design Process

The design process has its own layers of communication even before CAD comes into play.  Often, a team works to define what garments should be included in the next season.  This team includes the front end.  The sales team will deliver the previous season’s sales statistics.  They would take note of core products and seasonal trend products with high sell-through.  The design and merchandising team then take a look at some of the market research to determine what’s trending.  Their market research will be specific to their customer demographic.  At this point, they define from a high level what some of the most important garments are to offer in a season.

For example, this conversation may conclude that specifically for Fall 2017 in the women’s jackets category, they need 1 Black Blazer, 1 Field Jacket, and 1 Embroidered Satin Bomber.  Images and physically samples will be pulled for inspiration boards to inform the design of their product.  These can range from street fashion blogs to historic references.

It is often not until later in the process, after discussion and feedback, that the collection is turned into a series of garments with detailed design features.  Those drawings are often used to communicate with the design team who will interpret the drawings into Illustrator sketches, known as flats, as discussed above as CAD 1.  This is one example of the fashion design process.  Often at larger companies, there is no original design sketch.  A department will be responsible for a single category and design the specific trending SKUs for that category independent of other departments.

Simulation and the Apparel Process

The question of why it is done this way brings up the assumption that maybe it could be done another way.  Could simulating garments in CAD offer solutions to some of the complicated logistics involved in this process?  Is the new design skill for Apparel going to be computer rendering?

There are a number of reasons why simulation gets brought up for use in the apparel space.  For one, visualizing garments before they are physically fabricated could reduce the rate of revision, hypothetically making the design process faster.

Fit and Design Detail

Using simulations could be helpful for refining design details earlier in the process and also for refining pattern making and fit.  There are several reasons why brands might not adopt this method… yet.

  1. Currently, simulating garments in non-intuitive, time consuming, and require a specific expertise that a fashion company may not have in-house.  In the end, it may be cheaper to make the garment than it is to simulate it.
  2. While simulations provide attractive looking graphics, they might not provide the information that the design team needs.  After sample making, the team checks the garment not only for fit but for construction details and manufacturability.  Is it being sewn together perfectly?  Where are problems and why?  Currently, no fabric simulation software addresses manufacturing processes for cut and sew like folders, guides, and other automation equipment.
  3. Designers aren’t the ones creating patterns.  Some brands use overseas patternmakers who work directly with factory sample makers.
  4. Tests like the Kawabata Evaluation System (KES) for gaining information about the physical properties of a fabric is time-consuming and requires specialized machinery in order to have a high accuracy model of specific cloth.  Watch here.
  5. Most of the time, brands are sensitive about which fit model they want to use to reflect the fit of their brand.  The brand usually doesn’t have a 3D scanner to input that model’s information into the simulation system and therefore cannot tell how the garment fits on the model.  It makes a difference to have a human reference that is both in the digital and real world.

Sales Tools and Future Possibilities

Incorporating 3D garment simulation opens up interesting new methods for selling garments.

The possibility of Crowd Funding offers compelling reasons to create simulated products.  While many people prefer to know that a garment does what it says it will, brands that have established a reputation could create a model for crowd-funding their designs at the beginning of each season.  Presales based on high accuracy simulations could increase interaction with customers and give insights into how much of a style should be produced, reducing waste significantly.

As Virtual Try-On evolves, people will be able to try on garments from their laptops and mobile devices.  It is already being expressed through Snapchat’s lenses.  This form of advertising currently may not reflect reality, but provides an entertaining experience to learn about new products.  Instore Augmented Reality could also make use of simulation…