Question

Describe two examples of automation technology that contributed to the development of additive manufacturing and why additive manufacturing would not be possible without that technology.

Design for X (DFX) is a design philosophy that emphasizes a single characteristic of a new product that will guide all of the decisions in the design of that object. What makes this a powerful strategy?

Describe two characteristics that assist with successful 3D printing that should be present in an object designed using Design For Additive Manufacturing (DFAM) as a guiding philosophy? (for example: having one large flat side that can adhere to a build plate)

Of the following: Design for Cost, Design for Reliability, or Design for Manufacturability, which is most compatible with production by additive manufacturing. Which characteristics of additive manufacturing contribute to that compatibility? why?

Answer 1

A) # Computer-aided design technology

Additive Manufacturing technology primarily makes use of the output from mechanical engineering, 3D Solid Modeling CAD software. It is important to understand that this is only a branch of a much larger set of CAD systems and, therefore, not all CAD systems will produce output suitable for layer-based AM technology. Currently, AM technology focuses on reproducing geometric form and so the better CAD systems to use are those that produce such forms in the most precise and effective way. Early CAD systems were extremely limited by the display technology. The first display systems had little or no capacity to produce anything other than alphanumeric text output. Some early computers had specialized graphics output devices that displayed graphics separate from the text commands used to drive them. Even so, the geometric forms were shown primarily in a vector form, displaying wire-frame output. As well as the heavy demand on the computing power required to display the graphics for such systems, this was because most displays were monochrome, making it very difficult to show 3D geometric forms on screen without lighting and shading effects.

#Laser

Many of the earliest AM systems were based on laser technology. The reasons are that lasers provide a high intensity and highly collimated beam of energy that can be moved very quickly in a controlled manner with the use of directional mirrors. Since AM requires the material in each layer to be solidified or joined in a selective manner, lasers are ideal candidates for use, provided the laser energy is compatible with the material transformation mechanisms. There are two kinds of laser processing used in AM; curing and heating. With photopolymer resins, the requirement is for laser energy of a specific frequency that will cause the liquid resin to solidify, or "cure." Usually, this laser is in the ultraviolet range but other frequencies can be used. For heating, the requirement is for the laser to carry sufficient thermal energy to cut through a layer of solid material, to cause the powder to melt, or to cause sheets of material to fuse. For powder processes, for example, the key is to melt the material in a controlled fashion without creating too great a build-up of heat, so that when the laser energy is removed, the molten material rapidly solidifies again. For cutting, the intention is to separate a region of material from another in the form of laser cutting. Earlier AM machines used tube lasers to provide the required energy but many manufacturers have more recently switched to solid-state technology, which provides greater efficiency, lifetime, and reliability.

##It is important to understand that AM was not developed in isolation from other technologies. For example it would not be possible for AM to exist were it not for innovations in areas like 3D graphics and Computer-Aided Design software. This chapter highlights some of the key moments that catalogue the development of Additive Manufacturing technology. It will describe how the different technologies converged to a state where they could be integrated into AM machines. It will also discuss milestone AM technologies and how they have contributed to increase the range of AM applications. Furthermore, we will discuss how the application of Additive Manufacturing has evolved to include greater functionality and embrace a wider range of applications beyond the initial intention of just prototyping.

B)

1.       DFx as a service

Assembly manufacturers know their business.They know what should work, and what may not work.As in-house assembly has been more and more outsourced, this knowledge is also more and more outsourced.Design houses, designers and OEMs rely on the knowledge and best practices of their assembly manufacturers to ensure that designs are manufacturable with reasonable yield and quality.(Almost all designs are manufacturable…it is a question of “at what cost?”).Why not make some money based on the value this knowledge provides?In fact, why not charge for reviewing the designs, even if that assembly manufacturer may not get the actual order to build.There is money to be made.If an automated DFx software system that has several hundred rules-based analyses runs a Manufacturing Risk Assessment and generates reports is purchased and implemented, and a knowledgeable process engineer or manufacturing engineer is put to the task of managing the Engineering Rules, reviewing the defects, generating the report and working with the customer, then all that’s left is to charge the customer.Is it really that easy?

1.       DFx to reduce risk to production

Being able to identify production stopping issues before production is immensely valuable.Wasted product and raw material, wasted time troubleshooting process problems, rework and re-ordering of material delays could seriously affect manufacturing cost or worse miss delivery deadlines to customers, adversely affecting customer satisfaction and future business.

A Dfx software system that can run Manufacturing Risk Assessment on the following categories would allow process engineers and manufacturing engineers make the adjustments, or go back to the customer immediately (not days after receiving the design package).

Supply chain risk – analyzing the Approved Vendor list and ensuring that all the Vendor-MPNs for a specific Customer Part Number called out in the Bill of Material are physically alike.  For those components that are not alike, exclude them from the ordering list for materials, right from the beginning.  If they are accidentally ordered after production has started, that order would immediately stop SMT Machines, as the recognition and shape definitions would fail.  A delay would occur. Costs occur.  Time wasted.

Joint solderability risk – Component footprints that are not designed well so that heel fillet or toe fillet distances are too small will create a situation whereby not enough solder goes down.  Is the stencil designed so that chip components have enough solder, but not too much so that they are ‘swimming’.  Are there ‘shadowed’ joints behind taller or wider components on boards that that are wave soldered.  These and many other solderablity issues should be analyzed before starting production, so they do not add to rework cost.  A strong DFx software system would be vital.

Testability risk – What is the current coverage of test points to Nets on this board?  Do we have enough probe points to ensure we are covering all the Nets on the board?  These questions should be answered by the Dfx software system early on, so that design engineers can be consulted an updates to CAD can be made as needed.  Even if it is too late to make updates to CAD, this information can be provided to the Test Engineers to ensure they are aware of the potential issues to testability.

Rework risk – Components placed too close run rework risk.  A DFx software system running a good Manufacturing Risk Assessment should be configured such that large components that are prone to rework are checked to ensure they have enough access.  For example, Chip components or SOICs placed too close to a BGA would hinder rework, or rework at a reasonable rate.  If there are many parts to rework, these tight component placements may delay product delivery.  If there are component placed under other components or shields, it would be critical to automate the identification of those using the Design data, and know how to plan the production accordingly.

# Additive manufacturing is now considered as a new paradigm that is foreseen to improve progress in many fields. The field of tissue engineering has been facing the need for tissue vascularization when producing thick tissues. The use of sugar glass as a fugitive ink to produce vascular networks through rapid casting may offer the key to vascularization of thick tissues produced by tissue engineering. Here, a 3D printer head capable of producing complex structures out of sugar glass is presented. This printer head uses a motorized heated syringe fitted with a custom made nozzle. The printer head was adapted to be mounted on a commercially available 3D printer. A mathematical model was derived to predict the diameter of the filaments based on the printer head feed rate and extrusion rate. Using a 1 mm diameter nozzle, the printer accurately produced filaments ranging from 0.3 mm to 3.2 mm in diameter. One of the main advantages of this manufacturing method is the self-supporting behaviour of sugar glass that allows the production of long, horizontal, curved, as well as overhanging filaments needed to produce complex vascular networks. Finally, to establish a proof of concept, polydimethylsiloxane was used as the gel matrix during the rapid casting to produce various “vascularized” constructs that were successfully perfused, which suggests that this new fabrication method can be used in a number of tissue engineering applications, including the vascularization of thick tissues.