DTM Project
Inventive Problem Solving Case Study

DTM Corporation develops, designs, manufacturers, markets and supports, on an international basis, rapid prototyping and rapid tooling systems and related powdered materials and services. DTM's Sinterstation systems use the SLS_® Selective Laser Sintering process to create solid three-dimensional objects, layer by layer, from plastic, metal, or ceramic powders that are "sintered" or fused using CO₂ laser energy. For more information, visit http://www.dtm-corp.com

Description of Technological Problem

The SLS_® Selective Laser Sintering process uses multiple applications to produce a three-dimensional part. DTM’s long-standing (seven years) dilemma was that the delivery of an essential system resource to the part bed is hindered by thermal distortion, adversely affecting the quality and reliability of the process.

Project Objectives

• To provide experienced engineers with education on the Ideation/TRIZ methodology.

• To provide experienced engineers with interactive training on Ideation’s Innovation WorkBench System^™ (IWB) software.

• To enhance and accelerate the innovative abilities of experienced engineers with the Ideation/TRIZ methodology and IWB software.

• To demonstrate that experienced engineers can identify viable solutions to difficult technological problems faster and more economically than with any other inventive problem-solving technique.

Project Timeline (March 29 – May 30, 1999)

Note: DTM management decided to institutionalize the Ideation/TRIZ Methodology and software tools. Additional training seminars were scheduled for June and July, 1999.

SLS_® Main Heating System
(IWB Problem Formulator Diagram)

Selected Directions and Associated Ideas

DTM’s Project Team compiled more than 120 Directions^* and associated ideas to resolve the hot powder delivery issues associated with the SLS_® Selective Laser Sintering process. The following samples illustrate how the Ideation/TRIZ process helps to provide focus and new opportunities for innovative solutions.

^* Directions, as shown here, are automatically generated by the IWB Problem Formulator and are based on special models (called Problem Formulator "diagrams") of the system/problem of interest. Items appearing in parentheses represent particular function boxes such as those shown in the above diagram.

Direction: Find a way to do without [the] (Part bed heater) for obtaining [the] (Radiant thermal energy).
Associated Idea: Put a heater on the roller.

Direction: Find a way to protect [the] (Hot part bed) from the harmful influence of [the] (convection), (hot spots in part bed), and (Warm powder).
Associated Idea: Eliminate the dead air space behind the process chamber to increase the ambient air temperature.

Direction: Find a way to resolve the contradiction: [the] (Part bed heater) should exist to obtain [the] (Hot part bed), and should not exist in order to avoid [the] (hot spots in feed powder).
Associated Idea: Decrease the distance from the part bed heater to the part bed.

Direction: Find a way to do without [the] (Part bed heater) for obtaining [the] (Hot part bed).
Associated Idea: Microwave the part bed.
Associated Idea: Use powder additives that add heat when hit by a laser.

Direction: Find an alternative way to obtain [the] (Nitrogen), that provides or enhances [the] (Previous layer), and does not cause [the] (convection).
Associated Idea: Rough vacuum.
Associated Idea: Increase chamber ambient temperature.
Associated Idea: Heat the process chamber floor.

Direction: Find a way to resolve the contradiction: [the] (Nitrogen) should exist to obtain [the] (Previous layer), and should not exist in order to avoid [the] (convection).
Associated Idea: Incorporate updraft through the part bed with hot nitrogen for positive pressure to deflect cold convection currents.

Direction: Find a way to protect [the] (Smooth layer) from the harmful influence of [the] (Feed heater).
Associated Idea: Use a two-section angled feed heater to prevent cross-talk to the part bed.
Associated Idea: Install a heated grate in the top of the feed opening instead of a radiant heater panel with thermocouples to regulate the temperature. Add a deflector to feed heaters.

Direction: Find a way to do without [the] (Smooth layer) for obtaining [the] (Good part bed).
Associated Idea: Coarse apply the hot powder toothed roller and then smooth with a secondary roller. Normalize the wavy part bed.

Direction: Find an alternative way to obtain [the] (Feed piston), that provides or enhances [the] (Warm powder).
Associated Idea: Use a knurled roller with high counter rotational speed to fluidize the powder wave.
Associated Idea: Dispense powder in a metered wave; feed a smaller amount; break up the large wave into smaller wave(s).
Associated Idea: Double small roller; double small wave top feed.
Associated Idea: Triple small roller; double small wave top feed.
Associated Idea: Caterpillar heated feed.
Associated Idea: Angled belt feed.
Associated Idea: Planetary roller feed.
Associated Idea: Crop row feed with secondary roller to fill in the furrows.
Associated Idea: Spline shaft feeder with trailing roller.
Associated Idea: Helical spline shaft roller.
Associated Idea: Spline roller with trailing front to back vibrating blade (sets layer thickness).
Associated Idea: Heated snow globe feeder.
Associated Idea: Fluidize powder wave with heated nitrogen.
Associated Idea: Dense phase traversing pneumatic feed.
Associated Idea: Compressed powder and cheese slicer feed.
Associated Idea: Dual laser 3D fabrication using intersecting interfering lasers; sintering occurs only at the intersection of the beams.
Associated Idea: Sub-layer sintering.

Direction: Find a way to enhance [the] (Hot part bed).
Associated Idea: Increase radiative coupling between part heater and part bed.
Associated Idea: Increased coupling of cylinder heater.
Associated Idea: More uniform part bed thermal distribution.

Direction: Find a way to protect [the] (Hot part bed) from the harmful influence of [the] (convection currents) and (Hot spots).
Associated Idea: Decrease the dead air space behind the process chamber.
Associated Idea: Add condensers to collect fairy frost (ease of cleaning essential).
Associated Idea: Increase the thermal conductivity of the powder.
Associated Idea: Rotate the heater like a rotisserie.
Associated Idea: Rotate heater very fast and fire laser through it like a propeller.
Associated Idea: Oscillate the heater focus like a fan (up and down).
Associated Idea: Move heater rod side to side and scan at trailing edge.
Associated Idea: Mount heater to roller and fire laser horizontally behind the heater/roller. Roll, heat and sinter in one motion.

Direction: Find an alternative way to obtain [the] (Part bed heater), that provides or enhances [the] (Radiant thermal energy), but does not cause [the] (Hot spots). This way should not be influenced by [the] (Heater geometry).
Associated Idea: Fire laser from the side of the process chamber to drop the chamber height and eliminate the hole in the heater.
Associated Idea: Use a solid heater and split laser beam to both sides.
Associated Idea: Köler lens heater.
Associated Idea: Print head that deposits a laser absorbing material and the diode bar laser that sinters, both mounted on an XY plotter scan system.
Associated Idea: Charged particle electron beam steering ionized plastic particle accelerator machine.

Direction: Find a way to enhance [the] (Part bed heater).
Associated Idea: Find a different supplier.
Associated Idea: Segmented part bed heater with Köler illumination.

Direction: Introduce a field-intensifier to enhance the action of [the] (Radiant thermal energy).
Associated Idea: Add material to powder that enhances the absorption of thermal energy
Ideation comment: The above direction and idea confirms that the SMEs are developing a greater understanding of the methodology.

Direction: Provide better controllability to enhance the action of [the] (Radiant thermal energy).
Associated Idea: Alternate control scheme, fast heater, slow heater, decrease the distance from heater to part bed.

Direction: Increase the level of ideality of the object [of] [the] (Roller).
Associated Idea: Deliver powder without agitating/shearing it.
Associated Idea: Powder can be compacted and laid onto part bed like a sheet of paper.
Associated Idea: Translating belt feeder with belt suface velocity equal to the traversing velocity.
Associated Idea: Vibratory top feed hopper. Flow rate past chute is matched to traverse velocity.
Associated Idea: LOM style system which uses heat to fuse layers together.
Associated Idea: User laser to create powder. Use dot matrix firing pattern to weaken sheet so that part can be broken out.
Associated Idea: Extrude slurry/powder through nozzle such that thickness of stream is equal to the layer thickness. Match the traversing velocity of nozzle to the stream velocity exiting the nozzle.
Associated Idea: Foamed plastic from heated nozzle.
Ideation Comment: Here the SMEs are beginning to see similarities to copy machines and laser printers

Joint Lessons Learned

1. Communication between the appropriate individuals within each organization is critical to meeting mutual needs and overcoming challenges.
2. Concise objectives and timelines must be established to ensure that predetermined success criteria are met.
3. Selection of an appropriate technological problem, and assembling of a project team that is open to new methods and committed to solving the problem is essential to success.
4. Management of the project throughout the process (i.e., organization, focal points, milestones, coaching) can ensure timely results.
5. Being flexible and accommodating helps an enterprise integrate and adapt new methods.
6. Integration and adaptation of the Ideation/TRIZ Methodology and related software tools delivers benchmark results that are superior to any other inventive problem-solving technique.

Contact Information

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