• We want to encourage those of you who ENJOY our site and find it USEFUL to DONATE and UPGRADE your membership from active member to donating or premium membership. If you want to know the differences in membership benefits, please visit THIS PAGE:

    https://www.hobby-machinist.com/premium/

    Donating memberships start at just $10 per year. These memberships are in fact donations that help pay our costs, and keep our site running!
    Thank you for your donation, God Bless You

  • As some of you know, I have wanted to stop managing H-M for some time. It's a tremendous strain on my personal life. I want to set up my own shop. In September, September 15, to be exact, it will be 8 years that Hobby-Machinist has been in existence.

    We've seen a lot of changes. In March, 4 moderators left to start their own site. They took some of you with them. So now you have split loyalties. You know who you are. They didn't like my way of managing this place, and thought they could do better without me. They didn't. The only thing holding them together is that they hate me. Their site was down until mid July. That is why I wanted to stay involved on here until they could learn to run this place. But they wanted me to leave right away, without the training part.

    Anyway, I have been training VTCNC to run things here. Dabbler is going to learn too. I feel that they are ready to start taking over the operation. I will be here to help in case they need, but I don't think they will. Tony Wells is and will be here also to consult with. I will be doing backups, upgrades, and installing addons. Other than that, I don't want to know about this place.

    What about the 4 moderators who were disloyal? I don't care. It isn't my call anymore. I would think that, rather than fumble, they ought to come back and do good work. That's up to them. If they want to return to try to lead more members to their site, I am done caring. I suffered too much aggravation worrying about it. I don't plan to spend any more. What they do impacts on them. I have my own opinions including those of you who followed them there. No longer my problem.

    I am leaving this place in good operating condition, and financial condition.
    --Nelson
[4]

How to identify die casting vs CNC?

[3]
[10] Like what you see?
Click here to donate to this forum and upgrade your account!

NGrimberg

Swarf
Registered
Joined
Jun 6, 2018
Messages
3
Likes
0
#1
Hello! How do you know if a product was made using CNC machining or die casting? For example, a phone back cover. The Google Pixel 2 has an aluminum chassis. How can I tell if that was made using CNC or die casting? Any input would be appreciated!
 

rgray

Active User
H-M Supporter - Gold Member ($25)
Joined
Nov 26, 2012
Messages
979
Likes
497
#2
I'm thinking something like that is stamped.
Looking closely at cast parts you can see the parting line if they haven't gone to the trouble to remove it.
Cast aluminum is somewhat brittle so thin parts are likely not cast.
 

Asm109

Registered
Registered
Joined
Aug 29, 2017
Messages
187
Likes
204
#3
Casting requires draft. ie angles on vertical surfaces so the part slips out of the die easily. Requires a gate where the metal was injected.
Good design strives to keep the wall thickness constant. CNC machining has no such requirement.
Machining leaves cutter marks. Dead sharp inner corners are much more difficult to make No draft required.
Close visual examination will tell you what process made the part.
It could also be a combo. Casting with a bit of machining to hold a critical dimension or two.
 

derf

Registered
Registered
Joined
Oct 3, 2015
Messages
546
Likes
591
#4
Look at the cost. In the case of a phone back, it's a high volume part. That means it will be manufactured the most cost effective way....die cast.
 

RWanke

Registered
Registered
Joined
Aug 23, 2017
Messages
94
Likes
111
#5
Depends on the phone. I phone X sells for $1000. Supposedly all machined aluminum. Maybe that's why. :big grin:
 

Downunder Bob

H-M Supporter - Sustaining Member
Staff member
H-M Platinum Supporter ($50)
Joined
May 16, 2016
Messages
922
Likes
363
#6
Machined parts will usually have some visible mahine marks, unless they have been very well finished. Also virtually impossible to have square internal corners.

Die cast will usually have visible draft, also you can often see the marks left by ejection pins and sometimes sprue gates, and part lines are visible. However if the part is extensively machined after casting, not always easy to tell. A toolmaker who is familiar with die casting dies can usually tell. but for the novice not always easy.

If it's important to know can you post some very clear close up photos from various angles. We might be able to help.
 

mws

Active User
H-M Supporter - Silver Member ($10)
Joined
Jan 26, 2013
Messages
195
Likes
99
#7
Most all small metal electronics cases, particularly phones these days, are machined. The tolerances are such that it doesn't pay to cast such a small part which will then need to be machined anyway. So they just start with a punched blank and CNC the rest, and changes are easy if they need clearance for a different component.
 

Downunder Bob

H-M Supporter - Sustaining Member
Staff member
H-M Platinum Supporter ($50)
Joined
May 16, 2016
Messages
922
Likes
363
#8
Most all small metal electronics cases, particularly phones these days, are machined. The tolerances are such that it doesn't pay to cast such a small part which will then need to be machined anyway. So they just start with a punched blank and CNC the rest, and changes are easy if they need clearance for a different component.
High pressure die casting can achieve some pretty good tolerances. Back in the mid 60's when I was working as a toolmaker we made some dies that produced precision parts for a customer that did not require machining.

many said it couldn't be done. but we did it. What they meant was, that they'd never seen it done, afraid to stretch the envelope. Fear is always the biggest hurdle for achievement. I admit however, that nowadays, with high speed CNC it's probably just cheaper.
 

mws

Active User
H-M Supporter - Silver Member ($10)
Joined
Jan 26, 2013
Messages
195
Likes
99
#9
High pressure die casting can achieve some pretty good tolerances. Back in the mid 60's when I was working as a toolmaker we made some dies that produced precision parts for a customer that did not require machining.

many said it couldn't be done. but we did it. What they meant was, that they'd never seen it done, afraid to stretch the envelope. Fear is always the biggest hurdle for achievement. I admit however, that nowadays, with high speed CNC it's probably just cheaper.
Indeed! I suppose, given some of the external features I've seen on some cases that might be an option. All the ones I've opened show milling marks internally with no ejection pin marks. No doubt, the volume of these throw away phones produced would cover the price of a few moulds in short order. There's a fellow, Paul Hamler, on you tube that does some pressurized lost wax casting "at home". It's pretty neat. Where's there's a will...
 
[6]
[5] [7]
Top