Aluminum Extrusion Design 6 Mistakes Designers Make And .

Aluminum Extrusion Design6 Mistakes Designers Makeand How to Avoid Them

IntroductionToday, more and more designers across a number ofSo how do you ensure you get the most out of theindustries are using aluminum extrusions in theiraluminum extrusion process and ultimately get theproducts for two reasons. First, aluminum offers manyshape and performance you want?unique properties, such as its high strength-to-weightratio, corrosion resistance, and electric conductivity, toWhen designing for aluminum extrusions, practitionersname a few. Second, aluminum extrusions giveneed a good background in alloy properties, relativedesigners opportunities to create complex shapes thatmaterial and tooling costs, proper tolerancing, and thecombine functions that would otherwise require thelatest manufacturing techniques.production and joining of several different parts.Unfortunately, little time is spent on the extrusionprocess in design and engineering school. This lack ofknowledge leads to some common design mistakesaluminum extrusion manufacturers see when theyreceive a new profile design.This guide addresses six of the most common designissues and provides guidance to design engineerswhen designing for aluminum extrusion.Aluminum Extrusion Design: 6 Mistakes Designers Make and How to Avoid ThemPAGE 2

1. Incomplete DrawingsAre you guilty of sending your extruder a Solid WorksDepending on how quickly you need an estimate, thisdrawing with no details asking for a quote?back and forth may stretch out your timeline.Too often aluminum extrusion manufacturers receiveWhat can you do to avoid issues?rough profile sketches that provide very little of theKeep dimensions readable, traceable to the feature andinformation needed to produce a cost estimate oruncluttered. While CAD drawings are ideal, providingdesign review. Precise measurements are necessary toyour manufacturer with detailed, annotated drawingsunderstand the component’s dimensions and shapewith defined scale will eliminate much of the back andand determine the proper container size needed forforth that happens with incomplete drawings.producing the extrusion die.When this information is unavailable or unclear, itresults in a quote that is inaccurate. Without all thedetails an extruder can only provide a ballparkestimate. Once the “finer points” are provided yourestimate could go up or down dramatically.Additionally, without all the details the result is a lot ofback and forth between you and your manufacturer.Aluminum Extrusion Design: 6 Mistakes Designers Make and How to Avoid ThemPAGE 3

If two dimension lines show up close together, eitherWhen ordering Aluminum Fabrication:put a note on one dimension to clarify what feature itrefers to, or apply dimensions in a logical flow. And, Send a DWG AutoCAD file of the profile.indicate “exposed surfaces” on your design drawing so Send a PDF showing dimensions, tolerances andthe extruder can give them special attention andprotect the finish during both extrusion and postextrusion handling.any post secondary operations and call outs. If the shape is complicated, such as requirescompound miter cuts, cutout shape locations inrelation to extrusion walls, etc. and include a SolidSome additional recommendations to improve theWorks .STP file.quoting process. Include quantities and shipping requirements.When ordering Aluminum Extrusion Lineals, withoutFabrication: Send a DWG AutoCAD file of the profile so you andyour manufacturer can review the design togetherand get a weight per foot using AutoCAD. Always include specifications for coatings. Include quantities and shipping requirements.Aluminum Extrusion Design: 6 Mistakes Designers Make and How to Avoid ThemPAGE 4

2. Failure to Share the “Big PictureIf you received a drawing for this part, would you know if thealloy indicated was appropriate? Would you be able toaccurately assess the profile to ensure it would withstand arequired load amount, if you had no idea how it was going to beused?Designers often fail to share full product details with theiraluminum extrusion manufacturer, such as how an extrudedcomponent will be used in relationship to other parts and itsfunctional requirements, e.g. load bearing component, exposureto heat, etc. These details are critical for the extrusion engineerto determine the proper alloy, temper and other factors.Additionally, by not providing more details to the extrusionmanufacturer, designers miss out on valuable insights to maketheir product or component as production friendly as possible,and more cost efficient. Extrusion engineers, having designedthousands of profile dies, have a wealth of information to shareAluminum Extrusion Design: 6 Mistakes Designers Make and How to Avoid ThemPAGE 5

with product designers. By collaborating with your manufacturer, you can discover other areas tooptimize, such as delivery, quality, reliability, ease ofWill the part be under load? What types of stresswill the part encounter? assembly, testability, and opportunities where standardWill there be critical visual surfaces?profiles versus custom can be used.If confidentiality is a concern, your extrusion providershould be willing to sign a non-disclosure agreementprior to reviewing your drawings.What can you do to avoid issues?Share how your part is going to be used, the moreinformation the better. Some critical questions toanswer include: How will it interact with other parts? Do you have amating extrusion or component? Is the part Safety Critical? Will it be used in anAutomotive or Aerospace application, which havespecific performance requirements?Aluminum Extrusion Design: 6 Mistakes Designers Make and How to Avoid ThemPAGE 6

3. Expecting Sharp CornersOur next issues comes from designers mistakenly believingthat all corners will have sharp edges. Unfortunately, theextrusion process cannot achieve razor-sharp corners. Thereason for this is that sharp corners generate unnecessaryheat, which can translate into tearing on exposed surfacesand/or die breakage when the hot metal is pushed throughthese areas.Tearing is more significant with certain alloys, such as 6061which can get build up on the extruded bearing surface.As you can see in this image, there are no sharp corners. Byrounding the corners the hot aluminum flows easier, cooler andfaster through the die, which translates into greater costsavings.Aluminum Extrusion Design: 6 Mistakes Designers Make and How to Avoid ThemPAGE 7

What can you do to avoid issues? Best advise is to design for simplicity. Morerounded corners enable less drag on the die andreduce the build up of heat that wears down thesurface of the die. A radius of 0.5 – 1mm is often sufficient. Take notethat when you snap lines in AutoCAD the programdoes not know to include a radius unless told to. If a design requires sharp internal angles, such as aprofile to enclose a box shape, this can be solvedby incorporating a hollow mold. You can alsoutilize fabrication techniques to achieve sharpedges, but keep in mind the added cost to do so.Aluminum Extrusion Design: 6 Mistakes Designers Make and How to Avoid ThemPAGE 8

4. Creating Irregular ShapesWhen designing for aluminum extrusions, the morethinner areas. If the thinner sections do not fill properly,unsymmetrical or unbalanced a shape, the less likely itthe entire part could become compromised and twistis to remain straight or hold angles and generalduring manufacturing. Thus adjustments will bedimensions. While non symmetrical shapes can beneeded to the die and die testing before production,produced, metal flows less readily into narrow andwhich adds costs.irregular die sections, making distortion and otherquality problems more likely to occur.Similarly are issues with consistency and uniformity ofwall thickness. While it is acceptable to have a range ofwall thicknesses within a single profile, shapes withuniform wall thickness are the easiest to producebecause the aluminum alloy flows through the die atthe same speed.As with non symmetrical shapes, dies that have anunequal wall thickness can be difficult to producebecause the hot aluminum is forced fastest throughthe widest sections, while moving slowly through theAluminum Extrusion Design: 6 Mistakes Designers Make and How to Avoid ThemPAGE 9

The minimum wall thickness which can be extruded forAluminum Association Manual for standardaluminum is dependent on the extrusion force andtolerances.speed, the choice of alloy, the shape of the profile, desired surface finish and tolerance specifications.is hot when extruded. Look for areas of cupping tooccur and long legs sticking out of the extrusionWhat can you do to avoid issues?without support. Long legs have a tendency to fallWhen designing your profile, remember these generalrules of thumb: from side to side. Avoid thin walls. Designing a thinner wall to simplysave money and weight can often backfire. Mostsome alloys need to be cooled using water, whichwill distort the part to a degree. cost savings come from the ease of extrusion. Alloy plays a major role. As mentioned in issue #3,tearing is more significant with certain alloys. Also,When designing your components, try to achieve asmuch symmetry as possible. Review your runout surface. Remember the metalWall thickness tolerances should be approximately /- 10% of the wall thickness. Minimum wallthickness goes up as the extrusion shape getsIf you have concerns about your design, or you arenot sure if what you have designed is easilyextruded, bring your extruder in early in the designprocess. In the end you will save time and moneyby identifying issues before production begins.larger. In most alloys, for example, a 0.062 inchwall is possible in a 3 inch-wide shape but notpossible for one 10 inch-wide. Consult theAluminum Extrusion Design: 6 Mistakes Designers Make and How to Avoid ThemPAGE 10

5. Inconsistent DimensioningConsistency in tolerancing methods is every bit asspecified. Remember, extrusion tool makers constructimportant as consistency in dimensioning. As atooling at the bottom of the tolerance. This is done soreminder, tolerance is used to control the amount ofthat over time the tooling will wear and you will have avariation inherent in all manufactured parts, ingreater die life, thus reducing tooling costs andparticularly for mating parts in an assembly. The use ofdowntime for tooling replacement.plus/minus ( /-) dimensioning provides the allowablepositive and negative variance from the dimensionSome designers may opt to express dimensional datawith double minus or positive tolerances, which is alsoan acceptable style. It is important you select anappropriate style of tolerance specification for yourdesign as it can have a significant impact on productcosts. Also, seeing tolerances specified the same wayamong all drawings will make it easier for themanufacturer to interpret, saving time and reducingerrors.If you have custom specific tolerance specifications,and you have a document that calls that out, be certainto supply that document, or do not call it out on yourAluminum Extrusion Design: 6 Mistakes Designers Make and How to Avoid ThemPAGE 11