Intro­duc­tion of DMLS and SLM

Being able to quick­ly and cost-effec­tive­ly pro­duce com­plex met­al parts, or part pro­to­types, is a prob­lem in mod­ern man­u­fac­tur­ing, and met­al 3D print­ing solves this prob­lem very well. Whether it is a design­er or a man­u­fac­tur­er, met­al 3D print­ing is undoubt­ed­ly a best choice.

Among them, DMLS and SLM are the most wide­ly used technologies.DMLS (Direct Met­al Laser Sin­ter­ing) and SLM (Selec­tive Laser Melt­ing) are two very sim­i­lar pow­der bed fusion (PBF) tech­nolo­gies. Each tech­nique melts a spec­i­fied pat­tern of met­al pow­der using laser beams. By repeat­ing this process in suc­ces­sive lay­ers, the machines build up com­plex parts, often using advanced met­al alloys. DMLS is a trade­mark of EOS while SLM is a trade­mark of SLM Solu­tions. Both tech­nolo­gies ful­ly melt met­al pow­der instead of sin­ter­ing it the way most met­al 3D print­ing tech­nolo­gies do.

Attribute	SLM	DMLS
Laser point diam­e­ter	80 to 160 microns	40 microns (for small­er machines)
Num­ber of lasers	Machines with 1,4, and 12 beams are avail­able	4

8 design tips for Met­al 3D Print­ing

Of course, in order to print reli­able met­al parts, we need to under­stand and fol­low some basic rules when design­ing. Let’s take a look at these 8 tips below.

1.Wall thick­ness 

The min­i­mum wall thick­ness to ensure a suc­cess­ful 3D print with most mate­ri­als is 0.5mm. 

2.Pin diam­e­ter

The min­i­mum reli­able pin diam­e­ter is 1mm.

Small­er diam­e­ters are pos­si­ble, but will have reduced con­tour sharp­ness.

3.Hole size

For accu­rate prints with no sup­port use hole diam­e­ters between 0.5 mm and 6 mm.

Sup­port free build­ing with hole diam­e­ters between 6 mm and 10 mm is ori­en­ta­tion depen­dent.

Sup­port struc­ture is required when hor­i­zon­tal holes with diam­e­ter of 10 mm is used.

4.Escape holes

Holes are need­ed on hol­lowed met­al parts so unmelt­ed pow­der gets prop­er­ly removed.

Bore hole diam­e­ter between 2 and 5 mm is sug­gest­ed.

5.Overhangs

45º is the min­i­mum angle where sup­port mate­r­i­al is not required.

6.Unsupported Edges

The max­i­mum length of a can­tilever-style over­hang­ing sur­face is 0.5 mm.

An over­hang­ing hor­i­zon­tal sur­face sup­port­ed on both ends can be 1 mm long.

7.Embossed Fea­tures

Embossed details must be designed using a min­i­mum height, oth­er­wise, it will not appear vis­i­ble. Such fea­tures should be at least 0.3mm. To ensure embossed details come out nice­ly, make them larg­er than the indi­cat­ed.

8.Engraved Details

Because of the heat-dis­si­pat­ing from the laser into the sur­round­ing pow­der dur­ing DMLS, text and engraved details are at risk of clos­ing up and won’t be vis­i­ble if not designed with a min­i­mum depth and width. Engraved details should be at least 0.5mm deep and 0.5mm wide.

Com­mon­ly used post treat­ment

1.Polishing

The process of cre­at­ing a smooth and shiny sur­face by rub­bing it, leav­ing a clean sur­face with a sig­nif­i­cant spec­u­lar reflec­tion.

2.Sandblasting

Pro­pelling a stream of abra­sive mate­r­i­al against a sur­face under high pres­sure to smooth a rough sur­face, rough­en a smooth sur­face, shape a sur­face or remove sur­face con­t­a­m­i­nants.