What is the Difference Between Direct Metal Laser Sintering and Selective Laser Sintering?

What is Selective Laser Sintering?

In SLS, a laser is used to sinter powdered metal, which means it fuses the metal together by applying heat from the laser Parts are built up one layer at a time by moving a build platform under a laser, which traces a pattern in a thin layer of powder atop the platform. The laser then fuses the powder together, causing it to solidify. The build platform then descends by one layer thickness (0.1-0.3mm), and the laser traces a new pattern in a new layer of powder.

Selective laser sintering (SLS) is a process that uses a high-powered laser to fuse very fine particles together into solid objects by selectively melting them into place in successive layers. SLS is an SLM process; however, unlike DMLS, SLS uses powdered metal rather than powdered plastic as its raw material. It has been used to fabricate prototype parts for end-use applications in aerospace, automotive, medical devices, consumer goods, and more.

SLS is typically used for smaller parts because the build volume is much smaller (7” x 5” x 5”).

Rapid Prototyping (RP) is a common term that is used to describe the process of fabricating a component through AM. Rapid Prototyping can be done with either an SLM or an SLS machine. The purpose of RP is to create a component that can be used for testing, evaluation, and demonstration purposes, or to create a model for the purposes of design development. In contrast to the production of end-use components, which is typically done using SLS, RP using SLM machines is typically done with materials such as nylon or polycarbonate and in smaller quantities than production runs.

 On the other hand, SLM RP using SLS machines can be done in larger quantities and with metals such as titanium alloys, stainless steel alloys, aluminum alloys and others—materials that are often unsuitable for RP using SLM machines due to their propensity for warping during fabrication and their higher melting temperatures. Moreover, SLM RP with SLS machines does not require tooling up; i.e., it does not require pre-production runs (which are usually necessary when starting with a new material) because it uses standard powder and laser optics that are always available on an SLS machine.

Where is Selective Laser Sintering Used?

SLS also has a specialized use case. SLS produces smaller quantities than traditional composite manufacturing methods due to the fine powder that melts during sintering. With this capability of low-volume production through multi-part print offers the opportunity for firms with unique processes where new molds are required every batch. SLS offers some flexibility in raw materials used through full color parts and a range of different polymers can be processed into solid form at low-cost.

Environmentally friendly recycled materials work just as well as virgin polymeric base materials used in each process- even carbon fiber filled composites can be processed as full color parts with SLS (where laser beam energy will convert filler particles into polymer). The typical strength difference between polymer matrix composites vs open-cell fourdiest frame-ups which pair up well with Selective Laser Sintering include:

Unibody Automotive Composite Parts and Components Lightweight frames for under-the-hood components Hot hatches encompass the majority of this market segment, where high levels of performance and consumer economy are demanded for much smaller mass vehicles.

Lasers have the potential to offer a lighter weight solution because their sintering process produces intercrossed filaments of Precipatated Nylon or polyurethane instead of using expensive toughened or tempered glass commingled with durable polyester resin. In one composite wheel project the hub and rim were manufactured together as a single part to significantly reduce manufacturing cost.

The additive manufacturing process produced a wheel in just seven parts, reducing tooling cost by at least 50% while costs were lowered further by avoiding costly post-processing steps like form cooling and green molding.

Other Sturdier Use Cases It’s not just automotive manufacturers seeing benefit from laser sintering processes, some other more traditional sturdier body parts include electronics housings, bumper frames, spoilers & side skirts; all utilizing additive manufacturing even if it’s through a variation of selective laser melting where plastic feedstock is loaded into an extruder until it’s fully melted & then fed into an SLM process.

What About Joining During Laser Sintering?

There are also building blocks against particular joining methods developed dowdiness seen in full color sand printed parts is not necessarily repeatable with SLS 3D printing, as denser recycled materials are typically used in this process.

The ability to process mixed material types lend well to being used at complex science sites since multiple security levels can be resolved while still meeting rigid design requirements of containment equipment, facilities and systems.

Who is the Best Choice to Offer Selective Laser Sintering?

Quick processing of complex molds or prototypes creates a demand for both 2-level Binder Jetting and Selective Laser Sintering, both which use an inkjet print nozzle to make each component by layering sintered powder only where powder is necessary. However, there may be a shift toward using entirely Laser Generated Melting or Direct Metal Manufacturing methods due to volume, price and detail level issues on printed sections of large molds/prototype tools (ie non-SLS surfaces) that may occur in some builds due to their unscientific approach.

With that said some applications do need color sand printed parts quickly which may require the services found at your local material supplier who can then complete these jobs in Metal Casting instead of releasing you into uncertain waters with China… that’s all they offer: 1) Structure 2) Spine and 3). Color (colored binder jet injection molded casts).

Then what? – Just good bye British! So it's still important to work with British partners whether they're Material itched or glued parts of sand, foams or epoxies are unsuitable for SLS manufacturing.

Surface Modification Overview:

A large number of materials used as laser-scanning 3D printer materials exhibit absorbance near the laser beam wavelength. This can cause several issues including poor quality output and variations in the printed layers due to thermal expansion.

 To address these and other issues we offer process services for parts manufactured in three dimensional laser scanning via our full color additive manufacturing systems, SLS.

SLS parts are usually only zeroed out on a bed of better material using temperature controlled support that is removed during the post production removal process of SDS processing (solvent, light and steam/carbon dioxide/Supercritical CO2) by our internal team in Hong Kong.

Differences between DMLS and SLS

DMLS and SLS are similar in that they are both SLM processes. They are also both used to produce metal parts. However, there are a number of key differences between these two additive manufacturing techniques. Let’s look at a few of the main points of differentiation.

• Build Volume - DMLS build volumes are very large (30” x 18” x 12” or larger), which makes this process ideal for larger parts. SLS is typically used for smaller parts because the build volume is much smaller (7” x 5” x 5”).
• Material - DMLS uses a powder bed (focused laser or a wide-beam laser), and SLS uses an unstructured bed of metal powder.
• DMLS can use alloys of many different metals, but SLS can only use one type of metal alloy.
• Part Geometry - DMLS allows you to build parts with complex geometry that would be impossible to build using traditional manufacturing techniques, but SLS is only suitable for simple geometries.
• Cost - The per-part cost of DMLS is higher than SLS, but the overall cost of the process (including design time) is lower. This is because DMLS uses a larger laser than SLS, and the materials used in DMLS are more expensive than the metal powder used in SLS that have been fabricated using DMLS.

DMLS systems are often used to produce “tooling” parts, which are often produced in small quantities. Tooling parts can be very complex and have features with extremely tight tolerances. Tooling parts can be used as molds or masters to make end-use parts by casting, investment casting, or machining.

SLM systems are sometimes called direct metal laser sintering (DMLS) systems because the 3D printing process they use is called direct metal laser sintering (DMLS).

 However, it is important to note that SLM systems are not limited to printing only metal parts; they can print with other materials like nylon and polycarbonate as well. Because of this, many companies today call their SLM systems Direct Metal Laser Melting (DMLM) machines or Direct Metal Laser Deposition (DMLD).

The term AM is also used to refer to SLM technologies; however, it is important to note that not all AM technologies use lasers and some laser-based AM processes don’t use powder bed fusion technology like SLM does.

Which is Better: DMLS or SLS?

DMLS is better for producing large pieces with complex geometry, but SLS is better for producing smaller parts with simple geometry. DMLS is also better for producing parts with a finish as smooth as that of an injection-molded part.

SLS, on the other hand, produces a rough finish that requires additional machining.

DMLS and SLS are both good for producing prototypes and small production runs.

With that in mind, you should use DMLS for large, complex parts that require a smooth finish. You should use SLS for small, simple parts that require rough finishes and would benefit from shorter lead times and lower costs.

Which process is right for you?

You need to weigh the advantages and disadvantages of both DMLS and SLS to determine which one is right for you. The table above can help you do that. The most important factors to consider are the size of the part you want to make and the geometry of the part. If you need to produce large parts with complex geometry, DMLS is your best option.

If you need to produce smaller parts with simple geometry, SLS is your best option. You also need to consider your budget. DMLS is generally more expensive than SLS, but it is also better for producing large parts with complex geometry. Overall, DMLS is a better process to use if you need to produce large, high-quality parts with complex geometry. SLS is better for smaller, simpler parts. fabricated with DMLS and other additive manufacturing processes. 

 DMLS offers a number of potential benefits for the FDM process chain, including short tool change times, high quality components delivered with high precision in both size and shape, enablement of shorter overall product development windows as well as accelerated time to market across multiple product generations. Additive manufacturing technology is used where design freedom permits use of advanced materials to achieve strength and flexibility without stiffeners or connectors through the complete build envelope.

Part Requirements

To create a part successfully using SLM processes, you should keep several key requirements in mind. Understanding requirements that the part must satisfy can help you select a process more easily and accurately. These capabilities are also particularly valuable when matching parts to specific AM technologies available to your team. The sketches used to create 3D models in SolidWorks  must adhere strongly to specific standards if they are to successfully populate the build platform, be scanned by an SLM machine, or printed using any other additive processes targeting the same output protocol type (like stereolithography).

Additional requirements for these processes include concern for dimensional accuracy, holes left after parts printed via any FDM or SLS process are not completely hollowed out from top layers from material deposited inside walls but only from material that made up the outside surface or wall thicknesses. Parts fabricated with an additive technology like

manufactured by DMLS, such as:

• A 50cc QuadruCopter go-kart (left) and a brake-drum hub for a Formula 3 race car.
• High-end jewelry, such as two five-ball diamond pendants; and a mechanical wrist watch.

Many high tolerance print jobs have been flown on major prototyping platforms using nozzle diameters of 0.2 inch such as those with EOS Direct Metal Lasers. As with SLS technology one of the main technological issues to consider is the appropriate way to get support material off the final part produced without pulling any or too difficultly, leading to tool failures or slowdowns to repair tool damage in AM process.

 Active support options include volatiles solvents on alloys that bond close enough to not come off while being blasted off with particles within liquified parts with no extra tool cleaning needed. Other tools would be optical and ultrasonic cleaning.

Processing Materials: Laser sintering(LS), Pulsed laser deposition Ag,SLD

Fabricating metal components at reduced cost is viewed by many as key for future offsetting raw material pricing volatility of materials costs or even price collapse that can lead uneconomic operations. Laser in the AM technologies provide unique technological opportunities that were 3D-printed in an SLS process.

The additive manufacturing processes that are covered in this book are grouped into three major families—plastic extrusion, printing, and sintering. These families each have their pros and cons—different advantages and disadvantages for different organizations and applications. The process you choose depends upon your requirements as well as a number of other factors, including resources (people, time, and/or money), industry dynamics (market demand), available service providers (technology choice), maturity in AM technology for the intended use (cost vs features vs safety), regulatory approvals (licensing or certification needs), your staffing capabilities, customer specifications, schedule constraints, intellectual property concerns (protection from design theft), and so on.

Whether AM is used to make prototypes or build final parts, these capabilities will empower people and businesses to accomplish great things. The ability to manufacture products right when they are needed will allow designers and engineers to go further faster than ever before.

 Setting the conditions for success in the areas of sustainability, economic growth, health care, education and the arts will be challenging over the next 10-20 years.

 Additive manufacturing advances offer new solutions where existing technology has failed us. I hope you embrace this opportunity.

 The future is additive!

Key Takeaway

DMLS and SLS are two additive manufacturing techniques used to produce metal parts. Although both processes are designed to produce metal parts, they use very different methods to do so. DMLS uses a laser to melt metal powders, while SLS uses a laser to sinter metal powders. DMLS can be used to produce large parts with complex geometry, but SLS can be used to produce smaller parts with simple geometry.

These two processes are both good for producing prototypes and small production runs. DMLS is better for producing large parts with complex geometry, while SLS is better for producing smaller parts with simple geometry.

Design for Additive Manufacturing (DfAM), or simply design for additive, is the process of designing parts to be built with additive manufacturing. DfAM involves more than SLM, and covers a wide range of considerations and processes to account for in CAD models and in the files used to communicate instructions from those models to a build platform of an AM system—design decisions have broad applications in making usable, functional parts that can withstand the stresses of 3D printing.

 Over time, design of parts to be 3D printed specifically with weight projections, infill density projections, layer thickness projections and smooth surfaces has evolved continually hence generating decreasing costs in production schedule linearly [3]. To see how designers are using these methods I would recommend you check out this anthology viewed at https://www.amazon. com/Design-Additive-Manufacturing-Proceedings/dp/0824835782 which intricately lists out great deal detail which emphasizes proper creation of tests on required joint structures .

A broad outline can be found at the site where most recent developments are met like “plastic” flow modeling physics coupled with algorithmic equations like finite element method used to generate velocity based on internal stresses when these effects penetrate into structure undetected; many definitions and forms apply for pressure extraction such as: proportional pressure calculation as created by angle calculations where total angle.

Note:

 that metal 3D printing is just one type of additive manufacturing.

FDM, SLA, and SLS also fit into the category of additive manufacturing. In many cases, metal 3D printing and other types of AM are sometimes incorrectly lumped together to form the catch-all term of 3D printing.

In this article you will learnt more about metal 3D printing but also gain a better understanding about the other building processes used in AM to get a more expansive perspective about this growing segment in the CAD/forging/CT delivering marketplace.

 We keep things simple by focusing on these five different processes in future articles:

• Electron beam melting (EBM)
• Direct energy deposition (DEM)
• Hot walls (HW)
• Laser additive manufacturing (LAM)
• Metal powder bed fusion method (MPBF).

Note that you can fuse any material into sheets—metal creates new opportunities in both production applications and art!

Rapid prototyping techniques such as stereolithography also fall under this umbrella.