Case study: Manufacturing parts for a medical scanner
A group of doctors approached Halo wanting 25,000 identical parts for manufacturing a medical scanner. When they contacted Halo, they were set on manufacturing via 3D printing, and already had a prototype ready. They were in the mindset to move into production.
It’s not difficult to imagine the mindset that these prospective clients had: 3D printing is straightforward and simple, so it must be an efficient way to manufacture a part. After all, the process of 3D printing is fairly easy. First is prototype creation, which the doctors had already done. Then comes printing.
3D printing works great when you need to create one or two parts. You can design almost anything you want, customize it to your tastes and specifications, choose a material for it, and then print the part.
However, the process is not necessarily the best option when you need a large number of identical pieces. This is because every piece requires the same amount of material, time, and energy to create. There are no benefits of economies of scale, which drives up the cost of materials and production time. Even with the prototypes already in place, the cost of manufacturing the doctors’ scanner part by 3D printing would be about $100,000 and the creation of the parts would take several weeks.
Exploring casting and molding
For this reason Halo suggested exploring two other options, casting and injection molding. Both casting and injection molding are established forms of manufacturing. John Hyatt patented the first injection molding machine over a century ago, in 1872. Manufacturers started extensively using both methods during and after World War II because of the huge demand for identical mass-market products.
These methods are typically not a viable solution if you need just a part or two, because the costs of creating a mold or a cast are high. That said, if you need to produce a large number of parts, the savings that you will get from using a mold typically offset the original expense of creating it.
Casting and molding are similar processes, in both of them materials are injected to form the final part. The main difference between casting and molding is in the materials used for casts.
Casting typically uses raw metals and the casts are made of steel. The advantage of casting is that is offers great accuracy. The ability to use raw metals only is the biggest disadvantage of casting. Because casting can only use raw materials, it is less robust and less versatile than injection molding. For this reason, casting usually costs less compared to molding.
In the case of the doctors and their device, casting would not be effective because of number of parts. To make 25,000 units would require several casts, which would drive up the costs of making new casts and make this option less. In this case, casting for manufacture of 25,000 units would cost $137,000, and the lead time would be around 1 month.
Molding is different from casting in that it uses polymer-based materials instead of raw materials. Combinations of different materials are also possible. This is typically more expensive, but also more durable, more flexible and leads to the production of stronger molds. All these parameters provide benefit when there is an order of large volume.
With 25,000 units that the client needed, Halo would be able to use injection molding to manufacture 25,000 units for about $60,000, and offer shorter lead time compared to casting and 3D printing.
Which approach is right for you?
Knowing about your options is the best approach that will help you accomplish your goals on time and within budget. 3D printing is not better than molding and molding is not better than casting. They all are different processes that vary in their effectiveness and efficiency based on the needs of a specific project. Here is what Halo ’s engineers look at when determining which approach to choose:
- Upfront costs. Injection molds and casts are expensive, but in case of a big order this expense is often offset.
- Production volume. 3D printing is great for the creation of custom parts. Molding and casting may turn out to be better options in high-volume projects, especially if the projects are spread over time. If you need to complete a large manufacturing project, consider how much of an initial investment you can afford and by when you need the production to be complete.
- Costs of materials. Plastics and combinations of various materials are usually more expensive than raw metals, but they offer unique benefits.
- Production time. Molds and casts may require some time to build, but after that production is fast. With 3D printing the production of each part starts from scratch. You need to think about your timeline and the number of units at each stage of your project.
- Overall costs and per-part costs. These are two important numbers you want to look at. The first number shows you your total costs. The second number shows costs per each unit. If you have a one-time project, you may have one set of demands. If you want a number of units in the near future but may need much more after that, looking at per-part cost and thinking long-term may be more important.
How can Halo help you?
Though here at Halo , we do specialize in 3D printing, 3D printing is not the only service we offer our clients. We bring a variety of engineering experience to the table. This allows us to help our clients reach their goals in the most effective and efficient way — be it time constraints, price, material restrictions, or something else.
Sometimes this means looking at options that have been around for many years, such as casting and injection molding. What matters at the end is not the technology but the results. Here at Halo , we understand that the value of technology is to serve our clients, not the other way around.