Learning Objectives
By the end of this section, students will be able to:
- Enumerate common reasons for using additive manufacturing.
- Describe the requirements for choosing an AM process.
- Enumerate industries where AM is in common use.
There are numerous reasons that people and organizations employ AM. Typically, we refer to the Project Management Triple Constraint of Schedule, Scope (or Performance) and Cost as the fundamental considerations. Digging further into the trinity, there are many sub-elements to consider.
- Schedule – Reducing production time or working inventory, compressing test or product development cycles, printing tools versus legacy means.
- Scope – Improving system and/or part performance through complexity or part count reduction, added functionality, improving durability, reducing CO2 emissions.
- Cost – Reducing cost of parts by improving assembly time and/or repeatability, reducing and/or expediting tooling time, design for AM improvements in part cost, reducing the number of parts that need to be produced, reducing the touch labor and processes in assembly, reducing cost to produce generally, and increasing revenue through enhanced performance.
To expand the Triple Constraints further, let’s explore some additional characteristics of AM design:
| Speed | Cost Savings | Performance Improvement | Complexity | Design | Durability | Lightweight | What Else? |
|---|---|---|---|---|---|---|---|
| no tooling net shape reduced machining |
multiple PCs fewer resources |
precise features eliminate leak points |
optimized internal fluid/air passages |
organic designs geometric flexibility |
design for stress | value added material only |
supply chain eco-friendly |
Speed
Additive manufacturing improves time to market. AM provides a fast track from concept to production where complex objects can be manufactured in a single process step. Innovations are designed, developed and tested more rapidly, eliminating the need for expensive and time-consuming prototype fabrication.
Cost
Inevitably, designers and engineers learn that taking weight out of a part leads to faster printing or faster build times. With traditional machining, more time on the mill often means lighter parts, but it costs more because of the time it takes to produce the part. With additive manufacturing, as we are adding material in a layer wise fashion, we think about weight and cost differently.
Complexity
This simply means that, with AM, parts can be designed with more complexity than before. As with all things, however, there are limitations. These parts can more closely follow a load path and, therefore, be lighter or more efficient in carrying load or stiffness.
Design
Sometimes this means adding design details in the form of functional features like cooling channels for tooling. Complex passages can be utilized, because there is no drilling required; therefore, you can manage the critical things like turbulent flow and pressure drops. This can lead to performance advantages when truly optimized. Other performance advantages allow the designer to include features that would otherwise have to be added in a secondary operation.
Durability
The durability of parts can be enhanced primarily through elimination of mating parts or surfaces. Elimination of weldments, brazes, fasteners, etc. create structural inefficiency. Unitization, or the combination of multiple parts via AM, is more efficient and therefore more durable. Increasing durability is also possible through local or bulk additions of new material. Repairing, locally supporting, or adding material has the benefit of making parts that may come in contact with other parts more durable. In some cases, the ability to add material to a specific location efficiently will improve the longevity of the part.
Light Weighting
The ability to make parts lighter than their legacy designs is one of the most exciting elements for engineers when first introduced to AM. Because we are adding material layer by layer, we can achieve lightweight structures. Conventional manufacturing is largely subtractive, meaning it continues to add cost the more we remove material. In AM, you don’t pay for material that you don’t add.
Social
AM has benefits to society and the environment. Using less material and fewer operations reduces energy consumption, transportation, and logistics costs which have a direct benefit on the environment primarily through the reduction of CO2 emissions.
AM Process Selection
How does an individual or an organization decide on which AM process or processes to use? It will always be a question of commercial and technical requirements. Commercially, we are interested in things like the annual demand or throughput of parts, cost versus the legacy manufacturing method, lead time, supply chain maturity and risk. Technically, the overall size of the part, the detail resolution, the material, part performance, inspection needs, and surface finish factor into which AM process is suitable.
The combination of technical and commercial requirements creates a picture of what has to be true to deploy AM as a method. In one instance it may be as simple as we need a specific material and there are only one or two methods that use that material. In others, the overall size of the part will dictate the process selection. It could be that manufacturing speed and delivery of parts is a key driver as AM processes today still seem quite slow compared to their legacy manufacturing counterparts.
AM is Interdisciplinary
Just as AM process selection requires input from multiple groups within an organization, it is imperative that an AM project is also staffed with an appropriate skills mix. AM encompasses multiple fields of materials ranging from polymers to metals and ceramics. Manufacturing specialists will be interested in feedstock and process sensitivities. Design engineers have a newfound sense of freedom to design for complexity, but they need to consider which AM process is going to be used and the associated tradeoffs.
The technical community needs to be engaged early and working with manufacturing, supply chain, and program management which ultimately calls on the leadership to create an environment where the organization can be successful with AM. If all the parties mentioned are not present at some point, the risk of the AM project becomes higher. In Chapter 8 The Business of Additive Manufacturing, we further reflect on the organizational knowledge required for successful AM adoption.
AM in Use Today
AM found early adopters in the Aerospace, Medical and Defense industries. These sectors are distinct as they have a high mix and low volume of parts, meaning they make a low number of a lot of different parts. Tooling is particularly un-economical for this scenario because the tooling amortization becomes a significant component of the per part cost, but often hard to avoid.
The luxury goods and jewelry sectors learned that personalization brought with it a price premium and so have taken AM into the mainstream. Similarly, dental applications are small and bespoke creating a natural fit. Energy sectors have been researching AM for years as they share some similar characteristics to aerospace and in some cases even similar materials. High value, low part quantities drive the Energy sector to avoid tooling solutions when possible.
Most recently, automotive and heavy transportation have found successful uses. In automotive several factors are converging and driving intense interest in AM:
- Material substitution has matured and further light weighting now relies on re-design versus simply changing to aluminum from steel, for example.
- Electrification of cars needs lighter structures due to the mass of the batteries and electric motors.
- Performance and customization have shown to be a profitable segment using AM to make specialized components for higher end cars, like Formula 1.
All these industries are exploring the ability to create digital warehouses wherever possible to avoid keeping and paying for inventories of costly spare parts some of which may also be facing issues with obsolescence.