Design for drafted applications

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Designed for drafted applications.

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After completing this video,

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you'll be able to

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identify the various types of draft required manufacturing,

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use fusion inspection tools to validate a model,

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and understand the principles of drafted

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manufacturing and specific design requirements.

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In Fusion,

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we're going to get started with two supplied data sets,

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FFF quadcopter arm and drafted quadcopterAM.

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When we think about drafted manufacturing,

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we mainly think about injection molding,

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but there are many other types of molding and casting processes

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that require our models to have draft or taper on the vertical walls.

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So,

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mainly we're gonna focus on injection molding and casting.

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But it is important that you do understand that

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other processes like rotor molding or blow molding,

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and even things like vacuum forming and composites,

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all will require or benefit from having tapered walls

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in the direction of pull from the mold.

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So,

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first,

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what is taper and what is this draft that we're talking about?

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Well,

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when we think about the FFF quadcopter arm that's designed for 3D printing,

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Though vertical walls are all completely vertical,

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meaning that they are going straight up and down

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off the build platform on our 3D printer.

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This also means that they could be manufactured with CNC

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milling using a 2.5 or 3 axis process fairly easily.

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When we think about a drafted application of the same part,

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this means that the vertical walls are all tapered.

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And this is because,

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as we manufacture this part by injecting

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liquid plastic

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and allowing it to cool inside the mold,

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the tapered sections allow it to be automatically ejected,

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or rather ease in that ejection process,

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that way it doesn't get stuck inside of the mold cavity.

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So in some cases you may find that you can get away with very little amount of draft,

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but in many cases you'll need at least 1 to 3

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degrees of draft on the external faces of your part,

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and if you do require something like a textured appearance,

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you may need to go up to 5 degrees or more,

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depending on the overall size of your part and the depth of the external walls.

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So when we think about injection molding,

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that's the first thing that should come to mind is that we need to keep in mind

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that we will have a draft requirement.

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This means that any external features,

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things like the vertical walls,

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but also any internal features like pockets or cavities or even screw holes,

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all need to have a certain amount of draft.

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Depending on the manufacturing method and the company

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that you're working with to manufacture parts,

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they may have separate requirements for things like

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rounded corners on certain areas of your design.

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They may also ask you to make adjustments to your design

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based on the requirements for things like ejector pins

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that help push the part out of the mold.

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Keep in mind that these are all going to be general guidelines,

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and working with the manufacturer is going to

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be an important step in that design process.

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Now,

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in addition to the requirements of draft,

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we also need to keep in mind a consistent wall thickness.

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Now there are areas of this design that are thicker than others.

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So for example,

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we've got a thin wall section right here between this area

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and then around the screw boss,

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you can see that there is a larger amount of plastic material.

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This means that as we work with this design,

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we may have a manufacturer ask us to do a recess or a pocket in this area

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to reduce the amount of material.

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The main reason for this is as plastic cools,

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it begins to shrink.

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If we have mostly a thin section,

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let's say that's 1 millimeter or 2,

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and then we have a larger area where we may have 4 or 5 millimeters,

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this means that the outside skin of the part is

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going to cool or solidify faster than the inside section.

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And this calls what we refer to as a sink.

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This means that the plastic is going to start shrinking internally,

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and it's going to pull that external shaping.

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This can cause deformations in your part,

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making it unusable,

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or simply cause

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deformations that are cosmetic in nature,

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making the part less desirable.

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So when we think about this,

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we also need to keep in mind that

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many of these same guidelines are true for things like casting.

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When we're talking about casting or injection molding,

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we always need to focus on those draft angles,

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but again,

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the requirements for consistent wall thickness and

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specifically when we're thinking about casting,

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the,

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the need to ensure that we don't have sharp corners in

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our parts are going to be important requirements in our design.

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Oftentimes when we work with manufacturers,

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we'll have a first round reviewing our parts and then we'll get

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information or feedback on things that need to be adjusted or changed.

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When we think about those adjustments or feedbacks or just the designs in general,

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we do have some tools in fusion to help us

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identify those areas before we send them out for manufacture.

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So for example,

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in our inspection,

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we've got measure,

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we can look at just general size and shape of our part,

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but we also have a draft analysis.

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The draft analysis is a great tool to help

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us identify draft angle requirements on our part.

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For example,

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we can select the body.

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We can select the pull direction,

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so this is going to be the direction it'll be removed from our mold.

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And as we look at this,

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you can also see that we're identifying different colors.

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If we change the pole direction,

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for example,

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if we put the pole direction up here,

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you can see now the bottom is blue

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and the top is green.

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If we select the bottom face,

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it's going to adjust the direction which we're pulling from.

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We also need to think about the draft angle requirements

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and whether or not we need a tolerance zone.

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For now,

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I'm going to disable the tolerance zone,

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and I'm going to change the draft requirements to be -1 degree to positive 1 degree,

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because I know that's the draft that's on this part.

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You can see here now that the external section of our part,

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as well as all these internal pockets,

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is in green.

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As we rotate it around,

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the bottom side is in blue.

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This is because it can't be manufactured from that pole direction.

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It's on the bottom of our part.

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Now that doesn't mean that the part itself can't be manufactured,

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it just means that the draft or the taper is in a different direction.

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If we add it in our tolerance zone,

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you'll notice that the top is still green,

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the bottom is still blue,

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but all of the inside sections are yellow.

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There are some areas where corners are still green,

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and you'll notice as we zoom in,

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There are several areas where it starts to transition to yellow,

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and what this is telling me is that

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these areas that are green are still well within our draft requirements.

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The areas that are yellow are falling into that tolerance zone.

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This means that they may be around the 1.5 degree mark.

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So if our draft requirements have this tolerance zone that

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we can float above or below those draft requirements,

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having the tolerance zone turned on can be very helpful.

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In most cases,

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you'll likely find that turning this off and

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using the firm numbers for a draft angle,

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in this case,

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is going to be a better indicator on whether or not the part can be manufactured.

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If we change these requirements to be plus and minus 1.5 degrees,

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you can now see that the areas are red,

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are going to not have enough draft to meet those requirements.

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So using this tool can be extremely handy and helpful

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to ensure that you've done all the appropriate design work

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before you send this out for quote and manufacture.

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So as you prepare for the certification,

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it's a good idea to have a basic level of understanding on

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just general idea on which drafted applications exist,

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things like injection molding,

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casting,

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and some of the other basic molding processes like

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blow molding and roto molding.

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You won't need to know specifics about them,

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but you will need to understand

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that there are different types of manufacturing methods aside

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from things like 3D printing and CNC machining.

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That do require your designs to have a different design approach,

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specifically with draft angle.

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You'll also want a basic understanding on design rules.

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You won't need to know all design rules,

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but

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basics such as consistent wall thickness,

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draft angle,

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and whether or not your specific parts,

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for example,

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casting,

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would be better off with rounded corners as opposed to square corners.

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So,

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look into those design rules,

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make sure that you have a basic understanding around

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those sand casting and basic injection molding rules

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before you go in and take the certification.

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Now,

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after you're done,

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make sure you move on to the next step.