Appropriate Compounds/materials

[Jacoolo]

<h1 style="font-weight: bold;" ="ips_pagetitle">Appropriate Compounds/materials For Housings Of Power Corded Tools
</h1>Hello guys



I want to obtain information about appropriate scope of materials
considered for housings of power corded tools like heat guns or drills?



Particularly, I am interested in restriction those compounds have to pass regarding following norms: LVD, EMC, MD



thx in advance



Jacek

 

[brent.drysdale]

Hi Jacek,
I don't know of any specific list and all designers I know just build up their knowledge over years.
There are some ways you can try:
- You can join IDES.com and look at plastics materials there (more searchability for properties with the professional version). You can search on MatWeb. Usually this sort of searching is long and tedious and you don't know what you are missing.
- You can ask the question directly to suppliers of Plastics materials. Depends on where you want to get your raw plastics as to where you might ask. Firms such as DuPont, Bayer, BASF, Sabic (was GE) and there are plenty more.
- Often for Power tools a reinforced Nylon is used but since this is not the area I work in I am not up to date with choices.

Hope this helps a little.
Regards, Brent

 

[Jacoolo]

Hello Brent

thanks for feedback. My current experience with plastic requires a little bit of expansion.

I feel still weak regarding discussed scope of use/products.




Edited by: muadib3d

 

[Jacoolo]

Hello guys

Ok so far I found out that PA6-GF30 is usually used in such parts.

The question is what type material is used for rubber finishing perfomed on handle?

 

[michaelpaul]

The question is what type material is used for rubber finishing performed on handle?

specifically, it's hard to answer. it's a TPE (thermoplastic elastomer). there are a number of manufacturers such as Santoprene and GLS.

you'll need to discuss your application with them and they'll be able to point you towards a compatible material. the biggest thing is that there absolutely must be chemical compatibility between the substrate (your nylon housing part) and the overmolded TPE. without good chemical adhesion, the TPE will not bond to the substrate and it will peel off. What bonds well to ABS may not bond well to Nylon and vice versa. talk to an engineer at the TPE manufacturer for guidance on the specifics.

 

[brent.drysdale]

Hi Jacek,
Nice Dune reference by the way (or at least I think that is what it is supposed to be).

I agree with michaelpaul that it is hard to answer

I have not used GLS products so can't say much about them. Have used various Santoprene grades but not for molding onto nylon. I would say that you need to discuss with your nylon supplier what materials they recommend that will stick to their nylon. In my experience delamination is one of the biggest issues for overmolding "rubber" onto a substrate so this is an area you need to get good advice on. I like TPU (polyurethanes) for overmoulding as this tends to have better chemical resistance for our purposes than materials such as Santoprene (Polystyrene based) but as always it comes down to looking at all facets of what you want to achieve and of course cost is usually a factor here.

Regards, Brent

 

[Jacoolo]

thx guys

brent - yes, Muadib comes from Dune. I was under big impression of this book. Aside - now, I prefere saga of Hyperion(D. Simons), much, much better

I expect nylon - PA6 to be used as major compound for plastic housing, and TPR(TPE) for rubber finishing. I consider creating extra fixing features to prevent TPR(TPE) from falling down.

I scheduled a meeting with compound supplier today - so I hope to find out something more, and then introduce small summary here.

 

[Jacoolo]

well, as promised, small summary

regarding material for main housings - PA6-GF30 was considered as not enough good if long time usage or heavy conditions are involved. Instead some kind of PBT, PET compounds.

TPE should be selected after amin compound was chosen so...this is clear

 

[Jacoolo]

ok, two cents more

I fetched data related to discussed topic from BASF and compared Makroblend family of compounds vs default PA6 GF30. My insights are following:

*none of them(Makroblend) comes close to PA6 GF30 if tensile stress at break is considered.

*however Makroblend compounds introduce explicit value of yield stress, PA6 GF does not cover this condition, in addition it has explicit strain at brake, which is not a case for mos of Makroblend compounds, so to me it means PA6 GF 30 is more "fragile".

Am I right? And if yes, still, how does it convert on right material selection for discussed scope of usage?

 

[brent.drysdale]

Hi Jacek,
Thanks for the Hyperion recommendation; I will have a look. I recommned the Saga of the Seven Suns (Kevin Anderson) as a very good Space Opera. Several big books = lots of reading

Back to work though.
I would be willing to bet every corded or cordless power tool I pick up uses reinforced nylon for the combination of properties and cost. There are so many different grades from many suppliers.

I have favoured PA6 based grades as It has been my experience that for our applications the better impact strength of PA6 versus PA66 is worth the drop in tensile strength. Grades I have used are B3WG6 30% Glass Filled, EMS-Grivory Grilon

 

[Jacoolo]

thx for input brent

More "ranting" - I`ll take a look on indicated books. I must admit I`ve read a lot recently everything apart of Si-fi, so it looks as good reason to get it back.

Well, PA6-GF30 exceeds Makroblend compounds if tensile strength is considered, however it fails when Impact strentgh is taken into account. So, you`re right.

I have got another question and I want to take this topic as advantage to ask before I launch new one.

So, I am up to develop new blowmold case for tools, and all conditions related to it I am very interested in. So if you know anything about following, let me know about it:

* material/compound appropriate for such implementation/scope of use

*technical condition one should consider for blowmolding - min. drafts, wallthickness, and so forth

 

[brent.drysdale]

Hi Jacek,
I have not directly been involved in designing for blowmolding but like most things I have kept an eye on it and of course I have opinions (for what they are worth).

When I was looking at blow molding some 25 years ago the process seemed quite crude compared to Injection molding with a far more variable output (this was extruded parrison > blow molding and the injected parrison > blow mold process was not around that I saw). But like most things in Plastics the more you dig the more there is to know. You will learn a lot by sectioning blow moldings you can get as samples. You will see thinning at sharper corners, typically opening at the top (covered with a closure) which has had the air for blowing the part, clamp off detail at the bottom, variable wall thickness mostly dependant mold geometry. You can often see undercuts in the tool especially at the base of the part. I don't know any rules or guidelines to help with design. Most of the extruded parrison blow molded parts use polyolefins though in older days a lot of PVC was used. Often there will be extrusion grades with longer chains used. Tools for blow molding are quite different from Injection molds. Often sand cast and machined tools are used; This is due to the lighter duty that these tools get compared to injection molds and also that blow molded parts are often used for packaging which changes frequently to make a "new' product. Typically the edges around the cavity are heavily relieved and sharpened to cut any excess parrison; at the bottom where the parrison is normally cut off there can be hardened inserts for better tool life. Wandering around a Blow Molding shop will tell you a lot.

The injection > blow molding used for things such as soft drink bottles is an interesting mix of technology. Lovely use of the bi diectional stretch properties of PET to get these bottles. Gives a very tight control of the original parrison but the blow mold is more complex to get the first stage stretch.

Not sure this helps much.
Regards, Brent

 

[hbrown48]

This is a very interesting thread and to be honest I never thought about
this. I am also of the opinion that this is very hard to answer.I will
definitely check all power tools I have at home because now I am
interested in the materials used for the housings. Most of the time I prefer power rental and maybe I can ask the provider if they now which material the housings are.