How To Print A 3D Model

Transcription

1 3D Rapid Prototype Printer Introduction Risks & Hazards General Safety Operating Safety Maintenance Operating Procedures Introduction The information contained in this SOP is general in nature. It is advised that operators are referred to the relevant manufacturer's manual for specific operating information. Rapid prototyping is used to quickly fabricate a scale model of a physical part or assembly using three-dimensional computer aided design (CAD) data. Additive manufacturing or 3D printing is a process of making three dimensional solid objects from a digital model. 3D printing is achieved using additive processes, where an object is created by laying down successive layers of material. 3D printing is different to traditional machining techniques (subtractive processes) which mostly rely on the removal of material by drilling, cutting etc. The use of additive manufacturing takes virtual designs from computer aided design (CAD) or animation modeling software, transforms them into thin, virtual, horizontal cross-sections and then creates successive layers until the model is complete. It is a WYSIWYG process where the virtual model and the physical model are almost identical. Fused deposition modeling (FDM) works using a plastic filament or metal wire which is unwound from a coil and supplies material to an extrusion nozzle which can turn the flow on and off. The nozzle is heated to melt the material and can be moved in both horizontal and vertical directions by a numerically controlled mechanism, directly controlled by a computer-aided manufacturing (CAM) software package. The model or part is produced by extruding small beads of thermoplastic material to form layers as the material hardens immediately after extrusion from the nozzle. Stepper motors or servo motors are typically employed to move the extrusion head. Various polymers are used, including acrylonitrile butadiene styrene (ABS), polycarbonate (PC), polylactic acid (PLA), PC/ABS, and polyphenylsulfone (PPSU). Traditional injection molding can be less expensive for manufacturing polymer products in high quantities, but additive fabrication can be faster and less expensive when producing relatively small quantities of parts. 3D printers give designers and concept development teams the ability to produce parts and concept models using a desktop size printer. The technology is used in the fields of jewelry, footwear, industrial design, architecture, engineering and construction, automotive, aerospace, dental and medical industries, education, geographic information systems, civil engineering,

2 and many others. The 3D Printing Revolution >>> Identified Risks and Hazards Hazards that may arise when operating 3D printing equipment include: moving parts inhalation of fumes electrocution from power faults, faulty equipment or incorrect use burns from hot materials Hazard Control All workplace hazards can be controlled to a certain degree using a variety of methods. The goal of controlling hazards is to prevent workers from being exposed to occupational hazards. Some methods of hazard control are more efficient than others, but a combination of methods usually provides a safer workplace than relying on only one method. There are five general categories of control measures: elimination (removal or exclusion) substitution (replacement or exchange) engineering controls (isolation or enclosure) administrative controls (organisation or management) personal protective equipment (least effective) The following control measures should included as part of the Safe Operating Procedures at your workplace. Personal Protective Equipment Pre-operational Safety

3 The following safety checks and precautions should be carried out when preparing to set up and use the 3D printer: Electrical equipment must be isolated from the main electricity supply when not in use. The operator should seek permission from the supervisor before using this equipment. Always check that the 3D printer is in good working. Check all settings carefully before commencing any printing operation. Position the platform and nozzle. The work area should be clean and free of equipment, rubbish and other obstacles. Ensure you have had instruction and training in the use the equipment. Operating Safety Precautions To avoid burning, or model deformation, do not touch the model, nozzle, or the platform by hand. Do not touch any other part of the body, while the printer is working or immediately after it has finished printing. When performing maintenance and product removal procedures, the machine and product may be hot and gloves are required to avoid burns. The printer must not be exposed to water, or damage may occur. Daily Maintenance On completion of the printing procedure, the nozzle may be covered with a layer of oxidized ABS. When the printer is printing, this oxidized ABS may melt on the nozzle, and may create discolored spots on the model. To avoid this you need to regularly clean the nozzle. Clean the nozzle after a print has been completed so the oxidized ABS is easier to remove. Lower the platform to the bottom on the Maintain dialogue box. Use some heat-resistant material, like 100 percent cotton cloth or soft paper. A pair of tweezers will also be required. Then clip paper or some other heat-resistant things with tweezers to clean up the nozzle. If you are using the special green paint on your platform, the platform requires cleaning after a few prints to get it back to a smooth surface. Simply remove the platform from the machine and soak it in water for a few hours and the paint will peel off easily. Once clean, repaint it with the green paint, or cover it with blue masking tape. Isolating and Lockout Switches Electrically operated machines should be fitted with a flush green on or start switch and a red stop switch that has a raised mushroom shaped head for fast emergency contact. As well as start and stop switches, all machines must have an isolating switch,

4 which enables the main power supply to be switched off when the machine is being set up, adjusted or when maintenance is being carried out. Safe Work Zones The following Safe Work Zones for this machine are derived from a state government education authority guide. Click here for a description of the zone requirements described in this diagram. Operating Procedures Always obtain permission from the supervisor before using the 3D printer. 3D printers should only be used used in a supervised location. In general, supervision should only be undertaken by teaching and support staff who are fully conversant with 3D printer safety, and any relevant risk assessments. Before using the 3D printer, you must have had instruction and training in its safe operating procedures. Check the following clothing for safety hazards and take appropriate action: Fasten any loose clothing and tie apron cords or straps at the back Remove any jacket or coat and any school uniform tie Roll up shirt sleeves above the elbows or fasten them securely at the wrists Wear appropriate Personal Protective Equipment such as safety glasses for eye protection. When using the Extrude function, keep at least 50mm between the nozzle and the platform. If too close, the nozzle may get blocked. The printer is designed to work properly at an ambient temperature of between 15 C and 30 C and humidity of between 20% and 50%; Operating outside these limits may result in low quality models. Put the ABS plastic spool onto the holder, and thread the ABS filament into the feeder and

5 press the travel switch. The filament will automatically feed material for as long as you hold down the switch. Remember to insert the end of the ABS filament into the filament tube. Appropriately placing your models on the platform can have an effect on print quality. In general, try to place your model in the centre of the platform. When more than one model is open, the gap between each model should be kept to at least 12mm to prevent the models sticking together. Before anything can be printed, the printer must be initialized. Click the Initialize option under the 3D print menu. The printer will beep and the initialization procedure will begin. The printer will then return the platform and print head to the printer s origin and beep again when it is ready. To print successfully, the platform should be set to start at a distance of 0.2mm from the nozzle. As each printer is slightly different, this distance needs to be calibrated before starting to print. An easy way to check the distance between the nozzle and platform is to fold a piece of paper in two (Which will make it about 0.2mm thick) and use that as a spacer to gauge the distance between the nozzle and platform. Once you have setup the nozzle height once, you do not need to do it again as it is automatically recorded in the Setup Screen. You may need to recalibrate nozzle height after moving the printer, or if you find the models are not adhering to the platform properly. If you keep adding new green paint on top of the old green paint, you may also need to recalibrate your nozzle height regularly. Before printing, the platform must be prepared so that the model adheres to the platform enough to be printed without the model moving while, at the same time, being easy to remove from the platform after printing. There are 2 options for preparing the platform. Method 1 The Green Paint from PP3DP: This is a special adhesive paint that you need to paint onto the platform. The platform should be painted with a thin and even coat of paint to achieve best performance. Method 2 3M Blue Masking Tape: Many users have reported successfully usingblue Masking Tape instead of the green paint. Simply

6 cover the platform with a layer of 3M blue masking tape and print onto the tape. Replace the tape when it wears out. For large models (over 40mm2) results can be improved by preheating the build platform. Click the Preheat option on the 3D Print menu and the printer begins to heat the platform. As a general rule, the slower you print, the better the quality of the parts. For tall parts, running at Fast speed can be problematic as the printer can vibrate to the extent that print quality is affected. For large surface area parts, the Fine setting can be problematic as the printer takes longer to print the part and the corners are therefore more likely to lift a little bit. Do not shut down the UP! System or pull out the USB cable when loading a digital model, or the model data may be lost. Once the print has started, you can unplug the USB cable from the printer. The print job is stored in the printer s internal memory, so the PC is no longer required. When the model has finished printing, the printer will beep, and the nozzle and platform stop heating. Gently slide the spatula under the model and slowly wiggle it back and forth to pry loose the model. Remember to use gloves as the platform and model may still be hot. The model is easier to remove from the printer when it is still hot. If you want to heat the platform before removing your model, use the preheat option. It is strongly recommended that you do not remove the model from the platform while the platform is still attached to the printer. If the model is removed with a lot of force while the platform is still on the printer, the mechanical structure of the printer may be damaged or its precision affected. CAUTION: The support material and the tools are sharp. Wear gloves and safety glasses when removing the part from the printer. The questions in the SOP knowledge test are general in nature. The manufacturer's manual is to be used to develop specific questions relevant to this tool or machine.