Requirements Justifications for v5.pdf

Justifications for Technical Requirements in the DLA PTC Additive Manufacturing Statement of Work

(v5, April 2024)

Paragraph Justification

3.1 Newly developed equipment cannot have a track record of reliability and supportability from the OEM.

3.1.1 This is standard warranty coverage for non-consumable parts.

3.1.2 They can’t hire the local Joe Handyman to fix it.

3.1.3 This allows for some time to get people and parts in place while minimizing downtime.

3.1.4 There is a lot of AM hardware and software from PRC.

3.2.1 FFF/FDM can produce the mechanically strongest prints for polymers and is a technology that is most familiar to associates in both test labs.

3.2.2 This is large enough to allow for production of useful brackets, trays, and fixtures in relation to the size of existing environmental test chambers and other PTC test equipment without the need for printing in multiple parts with post-process joining.

3.2.3 The only practical way to use both model and support material is to have at least two extruders.

3.2.4 ABS and ASA provide a lower cost material for prototyping and general use. PEKK and PEI provide high-performance options from the ultrapolymers that can produce prints capable of replacing metal parts. ESD-safe material will be necessary for certain fixturing and other applications in the EPTC. Support material is necessary for printing many different part geometries because using model material as support material risks damage to the model during support material removal. Materials with infused carbon fiber allows for increased strength and impact resistance at much lower cost when then use of PAEK-family materials is not called for.

3.2.5 Soluble support materials allow for the use of support material in enclosed areas where mechanical removal is not possible (e.g., interior chambers with small openings).

3.2.6 By keeping filament near its glass transition temperature for longer periods, chamber temperatures >= 190 °C allow for sufficient layer-to-layer adhesion in PAEK-family materials which achieves high levels of anisotropy (i.e., equal strength in all directions). A high degree of anisotropy is required in the EPTC for vibration testing brackets and fixtures. Additionally, high chamber temperatures are required at the time of printing to hold the transition from amorphous to semi-crystalline state in PAEK-family materials which is necessary for achieving the stated mechanical properties.

3.2.7 Different materials require different extrusion temperatures. PAEK-family materials require high extrusion temperatures for successful printing.

3.2.8 Cloud-based software will be difficult or impossible to get approval for.

3.2.9 Various filament types are very hydrophilic, and absorption of water negatively impacts print surface quality and strength. Filament spools can be kept in dry storage outside of the printer, but the printer must maintain <= 5% RH where the filament spools are loaded into the printer.

3.2.10 Automatic switching of spools allows for the use of spools with low remaining filament quantity without the need for constant monitoring and switching of spools.

3.2.11 The AM lab does not have special ventilation for hazardous fumes.

3.2.12 These are the power sources available in the AM lab.

3.2.13 This is the size of the door in the AM lab. All other clearances between the room door and loading dock are larger.

3.2.14 This is the maximum size the AM room will allow for considering layout and clearance requirements.

3.2.15 If there is a drying system, it needs to reside in the same room, and this is the max size we can rearrange for.

3.2.16 If there is a transformer, it needs to reside in the same room, and this is the max size we can rearrange for.

3.2.17 Work will need to continue in the AM lab while printing so the machine must be quiet enough to not require hearing protection.

3.3.1 No random 3rd party filaments that won’t work. No half or sample spools.

3.3.2 The atmospheric conditions described in 3.2.9 also need to be maintained during transportation and storage for sensitive materials.

3.3.3 For colored filaments, black will look professional. For uncolored filaments (e.g. PEKK, etc.), the natural color is fine.

3.3.4 If the printer manufacturer makes filament that meets the requirements, they cannot provide a 3rd party filament to reduce costs.

3.3.5 Consumable hardware must be for the model of printer provided.

3.3.6 Consumable hardware must be for the model of printer provided.

3.4.1 The washing station is useless if printed parts can’t fit in it.

3.4.2 This will prevent excessive loss of washing solution through evaporation and prevent excessive humidification of the lab spaces.

3.4.3 Using the washing station will be a regular occurrence in a space shared with other test equipment. This will prevent others working in the spaces from regularly needing hearing protection.

3.4.4 These are the power sources available in the environmental lab area where the washing station will be located.

3.5.1 Some scanned parts will have been manufactured to tight tolerances and we will need to capture the geometry precisely.

3.5.2 Larger parts may be scanned for use in developing fixtures or mating parts so the scanner must maintain high accuracy over larger distances.

3.5.3 Being truly handheld without being constrained by an enclosure or armature allows for scans that are much larger than parts that could fit on table or other fixture.

3.5.4 We need to, at the very least, be able to scan parts that the printer is capable of printing and be able to scan parts the printer has produced.

3.5.5 If the scanner is tethered, USB is in common use. If it is fully non-tethered, the removable media should not be proprietary or esoteric.

3.5.6 Blue lasers allow for the scanning of geometry with highly specular surfaces (i.e., shiny, polished, mirror-like surfaces) without the introduction of contrast agents required by red lasers.

3.5.7 The primary purpose of the scanner is to capture geometry for CAD use, so without appropriate software it Is useless. Also, proprietary output formats restrict our ability to work with the files in the scan-print or scan-inspect workflow.

3.5.8 The secondary purpose of the scanner is part inspection. If the inspection software can’t measure features on the same order of magnitude that the scanner hardware is capable of capturing, capability is wasted.

3.5.9 This laptop will need to be powerful enough to support scanner capture software. We will need administrative access to change networking settings.

3.5.10 The vendor must support these laptops because J6 will not.

3.5.11 3D scanning and inspection require specialized skill sets for using both the hardware and software. This will make sure that a number of individuals in both labs are comfortable utilizing the entire scanning system so it is properly utilized.

3.6.1 Four days will be a minimum required to gain basic familiarity with what is highly complex software. There needs to be a curriculum or lesson plan to keep the learning focused.

3.6.2 We will not have enough computers with SolidWorks for everyone to use one.

3.6.3 Training materials and files are incredibly useful for reference after the class.

3.6.4 These are the basic operations needed for modeling in 3D to allow for successful creation and editing for models for fixturing and other uses within the labs.