3D Printing Technologies

3D printing technologies are advancing rapidly, with recent innovations focusing on improving speed, material diversity, precision, and scalability. Here are some of the latest 3D printing technologies:

1. Digital Light Processing (DLP) with Continuous Liquid Interface Production (CLIP):

• Overview: CLIP is an advanced form of DLP developed by Carbon (a 3D printing company) that creates parts by projecting light onto a resin bath. Unlike traditional DLP, it uses a continuous oxygen-permeable membrane, allowing parts to be printed much faster and with better surface finish.

• Advantages: High-speed production with isotropic properties (uniform strength in all directions), making it suitable for manufacturing functional parts.

• Applications: Widely used in automotive, dental, and consumer products, especially where high speed and durability are crucial.

2. Multi Jet Fusion (MJF):

• Overview: Developed by HP, MJF uses a powder bed fusion process combined with fusing agents and detailing agents. A heat source passes over the bed to fuse particles, while detailing agents refine the edges for better accuracy.

• Advantages: High strength, smooth surface finish, fine detail, and faster print times compared to traditional SLS (Selective Laser Sintering).

• Applications: Ideal for functional prototypes, production of end-use parts, and creating geometrically complex designs.

3. Bound Metal Deposition (BMD):

• Overview: A proprietary technology by Desktop Metal, BMD uses bound metal rods with polymer binders that are extruded and then sintered in a furnace to form solid metal parts.

• Advantages: Safer and less expensive than traditional metal 3D printing (e.g., DMLS or SLM), and suitable for office environments.

• Applications: Great for producing metal parts without the need for a dedicated metalworking facility, ideal for tooling, functional parts, and low-to-mid-volume production.

4. Volumetric 3D Printing (V3DP):

• Overview: Volumetric printing uses light to cure a liquid resin in multiple directions at once, creating the entire part simultaneously rather than layer-by-layer.

• Advantages: Extremely fast print times, with some processes producing parts in seconds. Offers smoother surfaces and reduces stress that occurs in layer-based printing.

• Applications: Suitable for rapid prototyping and applications where speed is critical, though still in experimental phases for industrial use.

5. Directed Energy Deposition (DED) with Laser Metal Deposition (LMD):

• Overview: DED uses a focused energy source, such as a laser or electron beam, to melt metal powders or wires as they’re deposited layer by layer. Newer methods, like LMD, precisely control the deposition process.

• Advantages: Ideal for repairing or adding material to existing metal parts, can work with a wide range of metals and even create multi-material parts.

• Applications: Primarily used in aerospace and defense for component repair, and in industries requiring large, complex metal parts.

6. High-Speed Sintering (HSS):

• Overview: HSS is a powder bed fusion process similar to SLS but uses infrared-sensitive ink that helps accelerate the sintering process, allowing for faster prints.

• Advantages: High-speed production and better scalability for producing large quantities of parts compared to SLS.

• Applications: Suitable for consumer products, industrial parts, and high-volume applications where speed and cost-effectiveness are priorities.

7. Hybrid 3D Printing (3D Printing + CNC Machining):

• Overview: Hybrid 3D printing combines additive manufacturing with CNC machining in a single setup, allowing parts to be both printed and machined in sequence or even simultaneously.

• Advantages: Allows for high precision and better surface finish in metal parts, as machining refines the printed part’s quality.

• Applications: Used in industries needing precision-engineered parts with complex geometries, such as aerospace, automotive, and medical devices.

8. Bio 3D Printing (Bioprinting):

• Overview: Bioprinting uses bio-compatible materials or living cells to create tissues, organs, or bone structures layer-by-layer.

• Advantages: Provides a foundation for tissue engineering, regenerative medicine, and potential organ replacement solutions.

• Applications: Research and development for tissue engineering, pharmaceutical testing, and, in the future, personalized medicine.

9. Cold Spray Additive Manufacturing (CSAM):

• Overview: Cold spray uses kinetic energy rather than heat to bond metal powders to a substrate by accelerating them through a nozzle. This additive technique builds up layers without melting the material.

• Advantages: Avoids thermal stresses, making it excellent for repairing high-performance parts, especially those with high-strength alloys or heat-sensitive materials.

• Applications: Useful in aerospace and defense industries for repair and creating parts with unique material properties.

10. Programmable Photopolymerization (P3):

• Overview: Developed by EnvisionTEC, P3 is an advanced DLP process that enables detailed control over resin curing, allowing parts with both soft and hard sections in a single print.

• Advantages: Provides extremely high surface finish, control over mechanical properties, and speed.

• Applications: Medical devices, wearable products, and functional prototypes where parts require varied properties.

Stereolithography (SLA) is a 3D printing technology known for its precision and smooth surface finish. SLA uses a UV laser to cure liquid resin into solid plastic. The range of materials available for SLA has expanded significantly, allowing for specialized applications across industries. Here’s a breakdown of the main SLA material types:

1. Standard Resins:

• Characteristics: Basic, rigid, and cost-effective. Known for high detail and smooth finishes.

• Uses: Ideal for prototypes and visual models with fine details, like product design concepts and presentation pieces.

2. Engineering Resins:

• Characteristics: These resins have improved mechanical properties, like high strength, temperature resistance, and flexibility.

• Tough Resin: Mimics the properties of ABS plastic, with impact resistance and durability.

• Durable Resin: Offers low friction and high impact strength, ideal for parts that undergo wear and tear.

• Flexible and Elastic Resins: Provide a range of flexibility and softness, suitable for prototyping rubber-like or ergonomic parts.

• Uses: Functional prototyping, jigs and fixtures, parts requiring mechanical durability.

3. High-Temperature Resins:

• Characteristics: Can withstand higher temperatures, with heat deflection temperatures up to 238°C or more.

• Uses: Great for applications like casting, molding, and functional parts that will experience elevated temperatures.

4. Dental and Medical Resins:

• Characteristics: Biocompatible resins designed for medical applications, often certified for specific uses (Class I and II).

• Dental Model Resin: Used for creating precise dental models.

• Surgical Guide Resin: Biocompatible resin for creating medical guides used in surgery.

• Denture Resin: For dental prosthetics, including crowns and bridges.

• Uses: Dental models, surgical guides, clear aligners, and other patient-specific applications.

5. Castable Resins:

• Characteristics: Burn out cleanly in casting processes without leaving ash.

• Uses: Common in jewelry, dentistry, and engineering for creating cast molds for metals or ceramics.

6. Clear Resins:

• Characteristics: Translucent and can be polished to transparency.

• Uses: Optics, fluid flow testing, and parts where transparency is essential.

SLA materials are continually evolving, with manufacturers developing new formulations to match specific industry needs, pushing the material range for SLA technology further every year.

Each of these technologies is driving the 3D printing industry forward, unlocking new possibilities for materials, designs, and applications across multiple industries.

Design Process

SCAMPER:

Improving Products and Services:

It can often be difficult to come up with new ideas when you're trying to develop or improve a product or service. This is where creative brainstorming techniques like SCAMPER can help. This tool helps you generate ideas for new products and services by encouraging you to think about how you could improve existing ones. We'll look at SCAMPER in this article and infographic.

About the Tool:

SCAMPER is a mnemonic that stands for:

• Substitute
• Combine
• Adapt
• Modify
• Put to another use
• Eliminate
• Reverse

You use the tool by asking questions about existing products, using each of the seven prompts above. These questions help you come up with creative ideas for developing new products, and for improving current ones. Alex Osborn, credited by many as the originator of brainstorming, originally came up with many of the questions used in the technique. However, it was Bob Eberle, an education administrator and author, who organized these questions into the SCAMPER mnemonic.

Note:

Remember that the word "products" doesn't only refer to physical goods. Products can also include processes, services, and even people. You can therefore adapt this technique to a wide range of situations.

How to Use the Tool:

SCAMPER is really easy to use.

First, take an existing product or service. This could be one that you want to improve, one that you're currently having problems with, or one that you think could be a good starting point for future development.

Then, ask questions about the product you identified, using the mnemonic to guide you. Brainstorm as many questions and answers as you can. (We've included some example questions, below.)

Finally, look at the answers that you came up with. Do any stand out as viable solutions? Could you use any of them to create a new product, or develop an existing one? If any of your ideas seem viable, then you can explore them further.

Example Questions:

Let's look at some of the questions you could ask for each letter of the mnemonic:

Substitute:

• What materials or resources can you substitute or swap to improve the product?
• What other product or process could you use?
• What rules could you substitute?
• Can you use this product somewhere else, or as a substitute for something else?
• What will happen if you change your feelings or attitude toward this product?

Combine:

• What would happen if you combine this product with another, to create something new?
• What if you combine purposes or objectives?
• What could you combine to maximize the uses of this product?
• How could you combine talent and resources to create a new approach to this product?

Adapt:

• How could you adapt or readjust this product to serve another purpose or use?
• What else is the product like?
• Who or what could you emulate to adapt this product?
• What else is like your product?
• What other context could you put your product into?
• What other products or ideas could you use for inspiration?

Modify:

• How could you change the shape, look, or feel of your product?
• What could you add to modify this product?
• What could you emphasize or highlight to create more value?
• What element of this product could you strengthen to create something new?

Put to Another Use:

• Can you use this product somewhere else, perhaps in another industry?
• Who else could use this product?
• How would this product behave differently in another setting?
• Could you recycle the waste from this product to make something new?

Eliminate:

• How could you streamline or simplify this product?
• What features, parts, or rules could you eliminate?
• What could you understate or tone down?
• How could you make it smaller, faster, lighter, or more fun?
• What would happen if you took away part of this product? What would you have in its place?

Reverse:

• What would happen if you reversed this process or sequenced things differently?
• What if you try to do the exact opposite of what you're trying to do now?
• What components could you substitute to change the order of this product?
• What roles could you reverse or swap?
• How could you reorganize this product?

Tip 1:

Some ideas that you generate using the tool may be impractical or may not suit your circumstances. Don't worry about this – the aim is to generate as many ideas as you can.

Tip 2:

To get the greatest benefit, use SCAMPER alongside other creative brainstorming and lateral thinking techniques such as Random Input, Provocation, Reversal, and Metaphorical Thinking.

LINK

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Synectics:

Around the same time in the 1940s that Alex Osborn was developing brainstorming, W. J. J. Gordon was investigating the psychology of problem-solving. He was later joined by George Prince at consultants Arthur D. Little where they developed the basic principles of what was called ‘Synectics’. In the manner of warring gurus, they later disagreed and both left to set up rival versions of the process (although for this article, the differences are too subtle to trouble with).

‘Synectics’ was derived from the Greek word ‘synektiktein’ meaning the joining together of different items and reflects the early discovery of the synergistic effects of ‘banging things together’ where the creative equation of A + B = C illustrates how new ideas can be created from two old ideas. Synectics these days is very much alive and the methods are taught and used around the world.

What is in Synectics?

Synectics is a big bag of tricks, developed over many years. Not surprisingly, as it is dealing with the same subject, many of the rules and techniques are similar to many other approaches. Where Synectics scores, however, is in the additional methods and principles that it adds to get around the problems of such traditional techniques as brainstorming. Thus, although Synectics sessions are often very much like brainstorming, they are supercharged with additional techniques to assist in even greater success. Some of these methods are described here.

Headlining and in-out listening:

When you are giving an idea, how do you do it? In many situations, we tend to start with a preamble about the need for the idea, then give the idea itself, then add further justification. The problem comes when you look at what the listener is doing at this time. They hear your initial preamble, and, once they have got the idea, start thinking about ideas of their own. This means that just as you are giving your idea, they have ‘gone inside their heads’ and are not paying attention!!

This leads to two complementary principles. ‘Headlining’ is simply for the person giving the idea to state the idea up-front, adding clarification only if it is called for. This, of course, requires an environment of trust, which must be built before the session begins. The other method of ‘In-out listening’ is for the listener, who, when they have an idea, write it down quickly so they can return to paying full attention to what is being said, rather than rehearsing their thoughts and trying to find a space in which to interrupt with their suggestion.

The problem-owner:

When brainstorming with a group of people, all of  whom have some ownership of a problem, the trouble that often occurs is that they can all fall into judgement and evaluation at various times through the process. This is simplified and sorted out in Synectics by having a single problem owner, with all other people being there to help that person solve their problem. Where those other people also have some ownership of the problem, they can ‘take turns’ at being the problem owner.

This also overcomes the problem of being blinkered by the situation and the helpers should not know as much about the problem as the problem owner, as this might lead to them becoming blinkered also. This encourages ‘wild ideas’ which, although on the face of it may appear ridiculous, may in fact not be so silly after all or may trigger other very valid thoughts.

Springboarding:

Have you ever been in a creative session where people do not seem to be paying much attention to other people’s ideas? Springboarding is a simple method of helping to trigger other ideas through the wording of your idea. This is simply done by prefixing the statement with ‘I wish…’ or ‘How to…’. You can use other words like ‘Wouldn’t it be nice if…’ although these are longer. ‘I wish’ and ‘How to’ can also be abbreviated when written down as ‘IW’ and ‘H2’. Wishing tends to be used for more speculative ideas and ‘How to’ for more specific problems, although people also tend to have their own preferences.

Notice the difference that these suggestions have on your inclination to add to them versus adding one of your own ideas: ‘Make everyone understand’ or ‘I wish everyone understood’. The ‘I wish’ probably leads you to think more about how that may be done.

Wording ideas as springboards also acts as a psychological legitimization as it is easier to say things like ‘I wish the parcels delivered themselves’ rather than ‘The parcels should deliver themselves.’

Excursions:

Have you ever been in a creative session where the ideas have dried up, yet you are sure that there are more ideas that could be found, if only you could unblock yourself somehow? Excursions are simply exercises that drive up side-roads using different techniques to find ideas off the beaten track that can be brought back and used like any other ideas.

Synectics makes particular use of analogies and metaphors, as these give you access to whole new worlds which tend to be very rich in the subject-matter areas which leads to many new ideas.

For example, when looking for ideas on how to insert components into a circuit board, you may take the principle of ‘insertion’ and take a journey into other realms, such as swords, which get inserted into scabbards and other people! Shocking subjects can be quite useful as they also jolt you out of the current rut you are in. Swords often have a groove in to allow the blood to run along and act as a lubricant. This principle could be applied to component leads, using solder flux as the lubricant, leading to full soldering through a plated-through hold.

To discover more about Synectics, try the book ‘Innovation and Creativity’ by Synectics consultants Jonne Cesarani and Peter Greatwood, and published in the UK by Kogan Page in 1995. Another excellent book that is sadly now out of print is Vincent Nolan’s ‘Innovator’s Handbook’ (though your local library may be able find you a copy). If you want to get back to the roots of it all, the original book is call ‘Synectics’ and was written by W. J. J. Gordon in 1961. LINK

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TRIZ:

TRIZ, also known as the theory of inventive problem solving, is a technique that fosters invention for project teams who have become stuck while trying to solve a business challenge. It provides data on similar past projects that can help teams find a new path forward.

TRIZ (pronounced “trees”) started in Russia. It involves a technique for problem solving created by observing the commonalities in solutions discovered in the past. Created by Genrich Altshuller in the former Soviet Union, the Six Sigma technique recognizes that certain patterns emerge whenever inventions are made.

Features of the technique:

Altshuller found that almost every invention falls into one of 40 categories. Each is an area where invention and innovation took place. They include areas such as weight, length and area of moving and stationary objects, speed of the object, temperature illumination intensity, ease of operation and ease of repair.

In practical use, a project team stymied by a challenge can use TRIZ to analyze a matrix of similar challenges and their solutions.

When TRIZ is used:

TRIZ operates on the idea that someone, somewhere, likely came up with a solution for the challenge you currently face or something similar. Another guiding principle is that contradictions should not be accepted, but rather resolved.

It also provides an answer for those concerned that Six Sigma stifles innovation. TRIZ encourages innovation. As pointed out in a paper on TRIZ conducted by researchers at the University of Belgrade and Metropolitan University in Serbia, not all solutions involving Six Sigma can be found in the process itself.

This “inhibits the ability to identify the control variables. In this case, a methodology that can solve the problem outside of the process boundaries, such as TRIZ, is necessary,” the researchers wrote. Essentially, TRIZ offers a sophisticated, effective tool for clearing roadblocks.

The Benefits of TRIZ:

TRIZ works best in situations where other Six Sigma tools have not accomplished the task. It provides another way to find solutions during the improve phase of the Six Sigma technique DMAIC (define, measure, analyze, improve, control) or the design phase of DMADV (define, measure, analyze, design, verify).

TRIZ allows project teams to globalize an issue and find examples of how people have solved similar challenges. It’s a bit like the old saying, “There’s no need to reinvent the wheel.” It’s possible that teams won’t have to develop a solution on their own, because it’s already been done. On the other hand, knowing the possible combination of the 40 categories that might apply to a specific issue can also spark new ideas.

How TRIZ works and examples:

TRIZ translates problems from the specific to the generic. It then compares the current challenge with 40 different inventive solutions. This is because in his research, Altshuller found that:

Problems and solutions repeat across industries and sciences. Patterns of technical evolution repeat across industries and sciences. Innovations used scientific effects outside the field where they were developed. It also supplies potential solutions to apparently contradictory issues, such as wanting a more powerful engine that is lighter or wanting something to both operate faster and more accurately.

Most examples for TRIZ involve solving engineering issues, such as the invention of a new type of self-heating container as detailed by TRIZ Journal or creation of automation that can handle the simultaneous filing of 10 interlinked plastic cups with paint.

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A designer must be familiar with modeling machined, cast, and sheet metal parts. He must also know the best method of handling weldments, assemblies, and purchased parts. 

Design Process
Overview:  A successful machine design requires much more than just creating a part. With all of the possible manufacturing processes, materials and commercial products available, a great amount of thought must go into the design process. Unfortunately, the machine market is too broad to go into specific detail. Because we can can't explain every detail in the machine market, we have shared some of our thoughts and experience that will make your outcome much more successful. The following explains our thoughts that go into each design process phase.

The Problem:
The first step in the design process is to define the problem. Whenever you start a new design, even if it is similar to past designs, you need to define and prioritize the elements of the problem. Subdividing the problem into smaller problems may make it easier to find a solution. After finding solutions to each of the small problems, you integrate them into a single solution.

In machine design, you essentially break the machine into components and design them individually - solve the small problems. You then integrate them to design the machine - solve the large problem. This usually involves a team of designers so communication is very important.

Usually you inherit a design assignment from your supervisor, the Research and Development team or it is self-induced. Next, you determine what your design time is, what are the production numbers and what are your available resources. It is important that you thoroughly understand all aspects of the problem in order to find an acceptable solution.

To understand the problem thoroughly, communicate with all involved parties from the potential operators of the machine to managers. Next, build in artificial barriers for yourself. It is impossible for a designer to know everything about the problem, so you should embark on an investigation to increase your knowledge. 

Ask questions! In doing so, you may discover aspects of the problem that you may not otherwise have addressed. This means you have avoided setbacks. As a designer, you don't just want to find the solution to the problem. You want to find the optimum solution.

Ideas:
The Innovative Phase of the design process is possibly the most time consuming part of the design process. This phase may appear to be a waste of time or unproductive. You must think of creating a design that is competitive in the market, cost effective, and innovative. In order to achieve this, you should follow a few ground rules. 

First, avoid studying the specifics of the problem just yet. Thinking about the constraints may prevent you from generating ideas. Brew some ideas first, identify the criteria next, then study each of the candidate ideas for a solution.

Generate as many ideas as possible. A common problem among designers is that they proceed to the specific problem-solving stage too quickly, which can be limiting. Working with a small number of ideas can be quite discouraging because many of them may not work. Generate a large pool of ideas before proceeding. You may find that it is not a single idea that solves the problem, but a combination of ideas.

No idea is too crazy. No idea is too complicated. By generating ideas, you get your creative juices flowing. While the first, second, or twenty-third idea may not provide the solution maybe the twenty-fourth does. Brainstorming sessions are very worthwhile - bouncing ideas around with co-workers really helps with creativity. Often the great idea comes two hours after the session, when you're putting a box of frosted flakes in the supermarket basket. And that million-dollar idea is nothing more than a simplified version of the crazy complicated idea mentioned earlier.

Keep a positive attitude. Its true you don't know everything, but you've just learned a lot about the problem in the previous phase. Now that you are thinking creatively, something will click. Don't let yourself be intimidated by criticism. If you do, you may suppress that crazy idea that just might work.

Criteria:
Once you have a good pool of ideas, identify the specific criteria for the problem. You must be very thorough in this phase, so communication is again important. You must be on the same page as the Marketing, Business Development, and any other involved departments.

List out all of the criteria such as cost, the timeline, size, and the working environment. The success of the product hinges on comparing your ideas against this list of constraints.

As you compare each candidate idea with this list, it either does or does not meet the criteria. There is not in-between. If the candidate does not meet the criteria, can it be modified to meet the criteria? If it can not, it is time to throw it out.

Solving the problem does not mean you need to reinvent the wheel. If you can use existing designs or standard parts to decrease the design cycle and not compromise design integrity, do it. 

Look at your or your company's past designs. Are there design elements in past projects that can easily improve a candidate idea?

Look at your competitor's products to see how they do it. If you have a competitor, they must be doing something right. You can learn from the way they do things, either right or wrong.

Development:
Identifying the criteria and flushing the impractical ideas leaves you with a core set of plausible ideas. As you are doing this, you are entering the next phase in the design process when you materialize your ideas into concepts. After developing the concepts, evaluate each one to ensure an optimum design. Some designers prefer to sketch a basic layout.

Others create a block assembly of approximate size and shape in the computer. Most designers like to sketch a layout on a coffee napkin over break. (Napkins are a bit cheaper than paper and it gets them away from their desks.) However you materialize your ideas, try to keep the details to a minimum.

This step is important because it gives you a good feel for the size of the machine, makes you aware of general problems that you need to give more thought to, and helps you communicate your ideas to others. This is where you can also delegate some of your workload. 

You can even take this step a little farther if you create a basic sketch with some dimensions. Even basic dimensions help in determining bar stock or standard parts required. It gives you a better feel for the size of the machine you are designing.

Evaluation:
Developing the concepts may reveal unforeseen flaws, prompting you to eliminate them. Any remaining concepts should then be compared to the established criteria again. 

This time, however, the comparison is much more in depth. Establish the relative importance of each criterion. For a machine in a manufacturing facility, cost is likely to be much more important than appearance. For a consumer product, cost and appearance may be of equal importance.

Next, rate how well each concept satisfies the criteria. This process should reveal the best concept. Selecting the candidate that has the best ratings for the most important criteria ensures an optimum design.

The Solution:
Simply put, there are only three things to be concerned with in this phase: form, fit, and function. Modeling your design in detail, fitting the pieces together, and evaluating the design for proper function are the most enjoyable and rewarding parts of the job.

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Designing with CAD:

CAD Process:

Design requires careful planning during the entire process. Knowing how to use the available tools (In NX, CATIA, etc) is the key to creating successful designs.

Conceptualization:

Before creating your part, it's a good idea to conceptualize your design. Some designers begin with a 2-D layout or even a rough CAD model, which will be redone. Hand-drawn sketches can even be a tremendous advantage in getting started. Many good designs started as a rough sketch on a napkin.

For styled consumer products, many designers sculpt their parts out of clay or Styrofoam before ever attempting to create a CAD model. This can be useful in that you can create a mock-up of your part. You can study this crude prototype to determine both how functional and moldable it is. Quite often, the most obvious molding issues are revealed at this stage. Reshaping your part to make it moldable before starting your CAD model saves valuable time.

Orienting the Part:

The idea behind conceptualizing is to determine how to approach your CAD model. Think about your part in a mold tool. What features does it have and how are they oriented? Can the part be oriented in the mold tool so that there are no undercuts?

By answering these questions, you can determine the draw direction and parting line for your part. Then you have a starting point for your CAD model.

Modeling the Basic Shape:

Typically, you begin your model with a primitive feature, such as a block or cylinder, or by extruding a profile.

With plastic parts, you should first concentrate on modeling the main portion of your part. That is, the overall shape of the part without the individual features. This portion of your model has a nominal, uniform thickness.

Shape your part by adding additional features. Creating sketches to define split profiles is a good approach. You can Pad (Extrude) or Shaft (Revolve) these sketches to Split (Trim) the solid body.

Features such as pads, pockets and slots can also be used to help shape your part. You should already be thinking about Draft. Adding Draft features while creating the model in these early stages saves you time when preparing your model for tool design.

Adding features or padding (extruding) sketches may not always define the desired shape. You may find it necessary to create sheet bodies, surfaces or additional solid bodies. 

Doing this allows more flexibility in the way you can define the necessary shape. These bodies are commonly referred to as tools. Use these tools to Split, Trim or Remove material away from your solid body.

You also need to be thinking about Fillets (blends). Use this feature to eliminate the sharp corners of your model. Fillets are normally added after Draft features. It is nearly impossible to add draft to a model using a blended Taper (Draft) feature.

By concentrating on only the basic shape of the part, you can now use the Shell feature to easily give the part a nominal, uniform thickness.

Adding Features:

Now you can begin adding features such as snaps, ribs, and bosses. The reason for holding off on these features until now is that they typically have a thickness smaller than the nominal thickness. The Shell (Hollow) feature is used to define the nominal thickness, so these features should be added after the Shell feature.

Evaluating the Design:

Once you have completed your model, you need to check it. You can use operations such as Measure Between (CATIA) or Analysis - Distance (NX) to verify the thickness in different areas. Doing this gives you a chance to catch anything you might have missed. Correcting thickness problems allows you to avoid having to deal with sink marks after the part has started a test production run.

In NX Face Analysis on the Analysis Shape toolbar is another key tool for analysing your part.  Draft Analysis (CATIA) is another key tool for analyzing your part. This allows you to graphically note the draft angles. It can be quite easy to forget to draft some faces of your model.

Identifying problem areas on your model is an important step in the design process. Once a mold tool is cut, it can be quite expensive to modify. Carefully scrutinizing your design can easily save thousands of dollars.

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What is Design Specifications?

A specification (singular) consists of a metric and a value. For example, "average time to assemble" is a metric, while "less than 75 seconds" is the value of this metric. Note that the value may take on several forms, including a particular number, a range, or an inequality. Values are always labeled with the appropriate units (e.g., seconds, kilograms, joules). Together, the metric and value form a specification. The product specifications (plural) are simply the set of the individual specifications.

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Design in Context (Top-down Modeling):

Overview:  

There are many advantages to top-down modeling, the greatest being the ability to design or edit in the context of the assembly structure. It is important to understand the following concepts when using design-in-context principles:

- Define the new component before creating any parametric geometry when possible.

- Sketching in the context of an assembly.

- Switching back and forth between top-down and bottom-up methods.

- Creating sub-assembly files.

Switching Between Top-Down and Bottom-Up:

You can use a combination of top-down and bottom-up methods in defining the assembly structure. You can also use a combination of these methods in designing and editing individual component geometry. 

For example, in an existing assembly, you create a new component and a "black box" shape to define its location and overall size within the assembly structure. You can save this part, close the assembly, and design the detail of the component part using bottom-up methods. The combination of methods provides the best of both worlds: top-down for positioning and evaluating size restrictions and bottom-up for detailing the component without having to work with the entire assembly.

Creating Sub-assembly Files:

Remember, components are the piece parts making-up an assembly. These piece parts can be used in multiple assemblies and multiple sub-assemblies. Therefore, it is always a good idea for each unique piece part to have its own part file. Even these piece parts can have their own component piece parts. 

For example, a coupling may be a piece part in a large machine assembly but the coupling also has its own components (plates, shafts, and hardware). The coupling is an assembly itself and a sub-assembly in a larger assembly. 

The piece parts in the coupling assembly should not be added directly to the machine assembly as components. Instead, create an empty file to act as the coupling assembly file, such as coupling-assy, and add all of the related coupling components to this file. Now coupling-assy can be added to a larger assembly as a sub-assembly. 

When you add a sub-assembly to an existing assembly, all of the components are added as well. In terms of design-in-context concepts, use the Insert| New Product to create sub-assembly files before adding or designing new components. Doing it this way creates a sub-assembly structure that is much easier to manage and manipulate than if you simply add the components to the top level assembly. Be careful of using the Insert | New Component to create a sub-assembly. If you do this, the sub-assembly only exists within that individual Product file and cannot be accessed by other CATIA Product files.

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Creating a Bottom-Up Assembly:

Path: Insert | Existing Component

Key Points:

This technique is similar to building a toy with 'some assembly required.' The necessary components are already available; you just need to put them together.

Prerequisites:

• You should be in the Assembly Design workbench.
• Adding a Component to an Assembly Using Bottom-Up Techniques

1. Open bottom_up\bottom_up.CATProduct.

2. Select Insert | Existing Component. CATIA prompts you to select a product component to add the existing component to.

3. Pick Bottom-Up Assembly. The File Selection dialog displays.

4. Navigate to the required folder and open bottom_up\cu_bolt.CATPart.

5. Position the component using either the Positioning Compass or by selecting Edit | Move | Manipulate. To hide the component planes from view, expand the appropriate branch of the tree to reveal the planes and View | Hide them in the same manner.

6. Add the bolt three more times using the same process.

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Creating a Top-Down Assembly:

Path:  Insert | New Part

Use this to:

• Create an assembly without all of the components in place. This allows you to start the product design of a component from scratch.
• Create new components in an existing assembly. This allows you to consider size, space, or interference limitations.

Prerequisites:

You should be in the Assembly Design Workbench.

Creating an Assembly Using Top-Down Techniques

1. Select File | New. The New dialog displays. 

2. Select Product from the list and click OK to create the assembly.

3. Pick the product from the Specification tree, then select Edit | Properties and change the part number to top_down_assembly, the revision level to A, and the description to Assembly, Top Down.

4. Refer to the next process, Creating a New Component Using Top-Down Techniques to create components in this assembly.

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Creating a New Component Using Top-Down Techniques:

1. Use the product you created in the previous Try It.

2. Select Insert | New Part. CATIA prompts you to select a component to add the new part to.

3. In the Specification Tree, pick the product. The new part is added to the Specification Tree and displays in the Graphics Window. Since this is the first part, the part's origin is automatically positioned at the assembly's origin.

4. Select Edit | Properties and change the part number to first_part, the revision level to A, and the description to Part, First.

5. Add a second part to the assembly. Select Insert | New Part. CATIA prompts you to select a component to add the new part to.

6. Pick the product name in the Specification Tree. Click No to set the origin of the new part to be the same as the origin of the assembly.

7. The new part is added to the Specification Tree and displays in the Graphics Window.

8. Select Edit | Properties and change the part number to second_part, the revision level to A, and the description to Part, Second.

9. Pick a new part in the Specification Tree, then expand it. Double–click on the Part to begin modeling in context of the assembly. (Make sure you pick the part and not the instance of the part.)

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