AMTS STANDARD WORKSHOP PRACTICE. Vacuum infusion process testing and development

Transcription

1 AMTS STANDARD WORKSHOP PRACTICE Vacuum infusion process testing and development Reference Number: AMTS-TP Date: March 2011 Version: Final

2 TABLE OF CONTENTS 1 Problem statement Background Primary references Research Planning VIP Setup Atmospheric pressure Humidity and water vapour Fibre pack permeability and resin uptake VIP layout and network design VIP method example The mould Preparation of the mould Selection of reinforcement Resin and vacuum lines Selection and installation of resin feed lines Selection and installation of vacuum lines Vacuum bag Building of vacuum bag Resin trap Vacuum pump Attaching of the pump Ensure proper vacuum Prepare for infusion Selection of resin

3 5.5.2 Set-up of resin bucket Resin infusion Catalysing of resin and allowance for infusion Clamping of resin Testing Test 1: core material infusion Problem statement Materials used Equipment used Test monsters Test procedure Test results Conclusions Test 2: Resin infusion of flap 2 mould Materials used Equipment used Results Conclusion Conclusion

4 1 Problem statement Flap 2 moulds for the JS1 needs to be built and the possibility of using vacuum infusion needs to be investigated and tested. 2 Background With a dream of the perfect sailplane the JS1 project started in The name "Revelation" was added later when the amount of work involved in creating a high performance sailplane was indeed a revelation! The final result: best performance in its class, superb handling, pristine quality, outstanding safety and surprising affordability. (JS, 2011) Jonker Sailplanes is one of the many aviation manufactures that makes use moulds to produce structural parts like, fuselages, wings and flaps. These parts are generally parts that need a quality finished shape or contour. To achieve these contours, according to MORENA, July 1994, the moulds, tools and any models are necessary prerequisites for any moulded part or assembly. The composite material usage increase made it a necessity for more advanced mould and tool processes and materials. (MORENA, July 1994) Vacuum Infusion Process (VIP), more generally known as resin infusion, is an advanced laminating technique that greatly improves the strength and quality of composite laminating parts versus the conventional hand lay-up method. Applying the technology of resin infusion and laminate engineering, simultaneously, allows for optimization of strength to weight ratios. Resin infusion has numerous benefits and significant strength gains due to the method of consolidations within vacuum all at once. Due to the reliability of high quality results and potential elimination of errors by the laminator, less material can be specified. This along with the reduction of resin absorption, results in weight savings. Recently, both polyester and vinyl ester resins, supplies, materials, and processes used for resin infusion, have improved significantly. These improvements made it commercially feasible for a wide range of products. 3

5 3 Primary references The main sources used for this document are indicated below. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this document are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below: [1] Vacuum infusion diagram, Date of last excess: 4 March 2011 [2] PILOTDAVE, January How the vacuum infusion process works. Date of last excess: 4 March [3] FRAM building and sailing pages. February Date of last excess: 4 March [4] NAVA COMPOSITES Resin infusion explained. Date of last access: 16 Sept [5] LIGHTWEIGHT STRUCTURES BV Vacuum infusion strategies for yacht hulls. Last access: 16 Sept 2011 [6] POLIYA Ready to start resin infusion. Last access: 16 Sept 2011 [7] FIBRE GLAST, Vacuum infusion. Last access: 16 Sept 2011 [8] PERFORMANCE COMPOSITES. Resin vacuum infusion. Last access: 16 Sept

6 [9] AMT COMPOSITES Newsletter Spring 2011: Resin infusion. 6&NewsletterID=301412& ID= &HitID= &token=4fba5b1 38a28479d a3b5dac3fc Last access: 5 Oct 2011 [10] FIBRE GLAST, Vacuum Infusion - The Equipment and Process of Resin Infusion. Last access: 5 Oct 2011 [11] JS, Jonker Sailplanes. [Online] Available at: [Accessed 06 February 2012]. [12] MORENA, J., July Advanced Composite mold making. Society of plastic Engineers, Inc.: Krieger publishing company Malabar, Florida. 5

7 4 Research 4.1 Planning VIP Setup It is always good practise to start a new process with trails and tests. Flat plates of varying thicknesses and materials can be used as test samples to determine resin flow characteristics and test laminate structures. Ask for help in the industry and resin/fabric/vacuum bagging suppliers to get the basics. The VIP setup will vary for different size parts, but the basic layout and influencing factors will be discussed in this section. The key influencing factors of VIP is: Atmospheric Air pressure Humidity & water vapour Fibre pack permeability Resins viscosity & gel times VIP network design Atmospheric pressure The driving force in VIP is that resin is pushed into the vacuum created in the dry laminate by air pressure. It is therefore critical to know the air pressure/altitude of the working location. (Johannesburg 1753m) Table 1: Average altitude for the fraction of 1 bar pressure. Fraction of 1 bar Average altitude meter Feet ¾ ½ / / Humidity and water vapour Most vacuum films contents nylon which is hygroscopic, atmospheric humidity therefore affects it. It can become brittle and loos elasticity. In higher humidity conditions it can become too soft which makes it difficult to handle. It is therefore good practise to store bagging films in the conditions specified on the data sheets. 6

8 The following guidelines should be followed regarding humidity and water vapour: Reinforcement must be kept in dry conditions. In epoxy infusions water held in the fabric can often be seen to be pushed in front of the resin flow this can cause the bond between the sealant tape and the bagging film to fail. Excessive water can also affect the cure of the resin systems, cause fibre whitening, and generally reduce the quality of the finished laminate Fibre pack permeability and resin uptake Resin flow and permeability In theory Darcy s law and the continuity equation can be used to get a VIP process equation that can be used to predict the rate of flow. The main purpose of the calculations is to calculate the flow front evolution with time, in order to obtain all information to optimize the process. There are several software programs available for the optimisation of VIP, like ISFEMAT. The key point of the program s process of calculation is: 1. Permeability 2. Porosity of the material (fibres) 3. Flow viscosity (Resin) 4. Selected injection points. However, there is some impractibilities that the theory does not take in to account: Availability of data permeability data of most reinforcements can be difficult to obtain and often has a wide tolerance. Resin viscosity varies with temperature Using combinations of materials- different fabrics and core combinations and layup orientations produces different permeabilities. Ultimately there is no substitute for determining flow rates like practical testing and trails on proposed laminates under working conditions. It is always good to test the flow rate horizontally and vertically as it will differ due to gravitation and for vertical applications testing should also be done on infusion from below and from above. NOTE: In general the core flow path should be in the same direction as the resin flow path to ensure a higher flow rate and increased consolidation Practical calculations of resin uptake It is good practice to calculate the resin need for the infusion process, as to avoid mixing too much or too little resin. Depending on the method of epoxy mixing used, the resin uptake will either be converted to kilograms or to volume. 7

9 When epoxy is measured and mixed by volume, the calculated resin uptake in weight needs to be multiplied by the density of the applicable resin system to convert it to volume Usually all laminating fibre materials will provide the resin uptake either in uptake per square meter or uptake per weight (kilogram or gram). It must be noted that the resin uptake is not only dependant on fibres, but also on the tubes, flow meshes, peel-ply, flow channel and resin trap. The following table provides a general guideline on the calculation and conversion of resin uptake for all components of VIP, it should be noted that it is always useful to mix more resin than calculated when starting out and calibrate it as more projects is attempted. Table 2: resin uptake calculations Component General uptake Calculation method Fibre % of fibre weight Get information on datasheet, Weight all cut fibre Resin uptake = Weight x % Core Amount resin kg / m² core Area of fibre = length(m) x width(m) Resin uptake = Area x amount Flow mesh % of fibre weight Get information on datasheet, Weight all cut fibre Resin uptake = Weight x % Flow channel Volume Volume = π x radius(m)² x length(m) Resin uptake = Volume x density of resin Tube Volume Volume = π x radius(m)² x length(m) Resin uptake = Volume x density of resin Peelply % of fibre weight Get information on datasheet, Weight all cut fibre Resin uptake = Weight x % VIP layout and network design Figure 16 explains the basic layout of the vacuum infusion process. All applications are different and should be evaluated beforehand for layout of feed lines and flow meshes. A few example cases will be shown for a practical feel of the layout of large applications. 8

10 VIP network designing VIP network designing consist of the planning and locating of resin flow meshes, vacuum tubing, manifolds, vacuum bag sizes and mould preparations. There is no full proof recipe for this process, but general guidelines can be followed with practical testing to ensure a fool proof process for each application. This process comes more easily with more experience. General VIP network designing guidelines: 1. Resin flow meshes Resin flow meshes should end at least 75% from the end of horizontal applications and with very low vertical applications just before the vertical plane starts. Large vertical applications should have the mesh up to about 90% from the top, when infusion is applied from the top. The flow mesh must also stop a few centimetres before vacuum membrane systems, like the VMS2. NOTE: The exact distance could be determined through proper testing. 2. Mould flanges Mould flanges should provide enough space for release films, vacuum flow lines and manifolds. 3. Mould edges Moulds should be designed with no sharp edges on part surface and outer surface, as sharp edges could damage vacuum bags. All sharp edges should be covered with soft fabric, like felt. 4. Part edges Parts should be designed, as far as possible, without any sharp edges, as the sharp edges could result in possible damage of the vacuum bags and can result in preinduced stress in the laminate. In the case where it cannot be avoided, care should be taken to bundle the bag in the allocated area or provision should be made for corner enhancers. 5. Vacuum bag size The vacuum bag should be much larger than the mould and should preferably cover the whole mould and not just the part area. (Small bags can be mended together with sticky tape, but is not advised as this can result in probable air leakages.) 6. Vacuum ports Vacuum ports should be preferably situated on corners or the outside of the mould. More than one vacuum port can be used on larger applications. 7. Reinforcement orientation The flow lines of the reinforcement, especially the core materials, should be orientated parallel to the direction of resin flow, for increased flow rate. (It could be orientated perpendicular or on 45 in certain areas, to decrease the flow rate if necessary). Fibre orientation could also influence the flow rate and it is advised to infuse in the same direction as the fibre orientation that is the most. 8. Vacuum membrane systems The allocation of vacuum membrane systems is more accurate on larger structures and is also not always necessary on smaller applications. It is good practise to test first, but in general vacuum membrane systems will be placed on dry spots, on intermediate positions between resin inlets, on parts where resin flow mark offs will 9

11 influence the structure, on possible lock off areas. It can be used as spot locators or as continuous vacuum systems % laminate fibre fractions To achieve a desirable 45-50% laminate fibre fraction one should shut off the resin inlet when you've sucked in sufficient resin for a 1:1 ratio of fabric to resin by weight. Clamp the resin line and ensure full vacuum is being pulled on the vacuum lines connected to the VMS2. Once sufficient resin is in the system the vacuum bag will continue to distribute the resin evenly to all dry areas, while vacuum membrane systems will continue to extract air and volatiles and not the resin. 10

12 VACUUM INFUSION PROCESS TESTING AND DEVELOPMENT Figure 1: Vacuum infusion process setup [6] 11

13 Vacuum membrane systems Vacuum membrane systems, like the VMS2 from Richmond Aerovac, are systems that act as a resin barrier in the vacuum line. Vacuum membrane systems have the following advantages [9]: Figure 2: Richmond Aerovac VMS2 vacuum membrane system. [9] Reduces the number of vacuum ports required, as it works in lengths up to 50m with one vacuum port. Reduces the flange width requirements, since it is located on the laminate itself and thus no need for an extra wide flange on the mould. It sits flat under the vacuum bag and there are no burst risks, as can be experienced with spiral tubes and other network systems. Faster infusion. It allows the introduction of vacuum at intermediate points between inlet channels. This reduces the resin travel distance and thus speeding up the infusion process. No mark off on finished products. No resin drawn into the vacuum system and thus accurate resin content on the laminate can easily be calculated. Reduces the resin waste in vacuum tubes and resin traps. Eliminates the risk of vacuum lock off when implemented correctly Eliminates dry spots as it can be placed anywhere on the mould. Network design is greatly simplified allowing network designing to cover any problem areas easily. Can be used as continuous vacuum systems or spot location vacuum points. 12

14 Figure 3: Richmond Aerovac VMS2 resin barrier vacuum line. [9] 5 VIP method example Due to the complexity of VIP, it should be viewed as a trail-and-error process. The best method of understanding VIP will be to document each attempt and learn from each trail. It is good to keep track of all the resin flow rates, determine where the resin is reluctant to go and search for means of resin flow paths. Practising with small amounts of inexpensive materials before undertaking full scale projects will help eliminating budget over dues on testing. In a manufacturing environment, it is recommended to set aside at least 6 months for preparation and testing. First the general sequence of events comprising VIP is illustrated in the diagram below. [10] Figure 4: General VIP sequence of events. [10] For the purpose of explanation this SWP will focus on general set-up idea, with the notion that the laminate will be infused with the resin from a centre point. The resin will thus be pulled outward via the vacuum pressure. The final arrangements of the applicable example are shown in figure

15 Figure 5: Final arrangement a laminate with resin infused from the middle (without a vacuum bag). [10] The steps involving the process are as follows: 1. The mould Preparation of the mould Selection of the reinforcement Selection of the flow media and/or core materials 2. Resin and vacuum lines Selection of resin feed lines Selection of vacuum lines 3. Vacuum bag Building of vacuum bag Allowing for prohibiting resin from entering 4. Vacuum pump Attaching of the pump Ensuring proper vacuum 5. Prepare for infusion Selection of resin Set-up of resin bucket 6. Resin infusion Catalysing of resin and allowance for starting infusion. 14

16 Clamping of resin line 7. Experiment and test for improvement Typical variations in set-up 5.1 The mould Preparation of the mould VIP, like any other laminating process, requires moulds of good quality, thus rigid and finished to a high-gloss. The mould should have flanges at least 120mm wide for the placement of sealant tape and spiral tubing. Figure 6: Mould with laid reinforcement and flow media [10] After cleansing of the mould, the proper release agent (See SWP 36) should be applied accordingly. NOTE: Unique release agents may be required for resin infusion Selection of reinforcement Reinforcement selection of any laminate is important, but there are additional considerations when choosing it for infusion. Most fabrics will potentially infuse, but different weave styles and materials can severely slow down flow rates of resin. The following information is a simple guideline for the choosing of materials [10]: Fibre glass Most fibre glass fabrics have high permeability qualities providing good resin flow rates. In general looser weaves tend to infuse better as there is less crimping of strands. Continuous strand mat will generally infuse better than chopped strand, while both offer high permeability. The binder in chopped strand mat may prohibit flow rate. Continuous strand mat will avoid this problem. 15

17 Knit fabrics are popular for VIP, because it is knit not woven, thus avoiding crimping caused by weaves. The materials not only boost resin flow, but also add strength and bulk quickly. Carbon Fibre (Graphite) and Aramid fibres These fibres tend to infuse slower than fibreglass fabrics, but may be used if needed. To counteract the slow flow rate, flow media was found to greatly increase infusion rates. It is a good idea to experiment with materials like these, to properly determine and gauge flow rates. Spray adhesive Working with more complex shapes may impose the problem of fibre that does not readily sits flat on the mould. Spray adhesives is recommended to solve this problem. NOTE: Spray adhesives may interfere with the curing process if used in excessive amount, thus take care to use it in small to moderate amounts. Flow mesh Flow media is a unique concept to vacuum infusion. Resin will always travel on the path of least resistance; unfortunately most reinforcements provide a big resistance. Aiding in the resin flow is the purpose of the flow mesh. It is possible to infuse reinforcements with resin with the aid of a flow mesh; but it is rarely successful. The flow mesh is typically laid as a single layer between or on top of the layers of reinforcement. Flow media comes in several styles, from fast infusion times, to maximum conformability and even as both a flow media and structural core. 5.2 Resin and vacuum lines Care consideration must be taken in the setup of resin- and vacuum lines before the vacuum bag can be closed. Figure 7: Resin feed lines. a) A Spiral resin feed line. b) A filter jacket. c) the method of connecting the resin tubes to the feed lines if a filter jacket is used. [10] 16

18 5.2.1 Selection and installation of resin feed lines Resin is fed from a standalone source (usually a bucket). The resin feed line must be installed before the closing of the bag. The same tubing that is being used for the application of vacuum can be used to feed the resin up to the bag, but from the bag there is several ways possible to spread the resin through the laminate. [10] Spiral tubing Spiral tubing is a plastic ribbon that is coiled into the shape of a tube. This construction makes it possible for air or resin to enter or leave the walls of the tube throughout its entire length. Resin can travel quickly through the tube and simultaneously seep out along the way into the laminate. NOTE: Ensure to wrap spiral tubing in peel ply for easing removal. Filter jackets / vacuum membrane systems. Vacuum membrane systems are specifically designed for VIP en assist greatly with resin spreading. See paragraph The filter jackets or VMS is very usefull, but care must be taken with the connection to the outer resin tubes. Normally the jacket is laid down, a T fitting is put on top of it and a little piece of filter jacket, with a hole just big enough for the top tube of the T-fitting is fitted over the T-fitting, as illustrated in figure 22 nr c Selection and installation of vacuum lines A Breather/bleeder, which is used in traditional vacuum bagging to both absorb excess resin and drive vacuum throughout the laminate, is typically not used with resin infusion. Instead VIP extends the vacuum lines within the sealed bag. [10] For this purpose, spiral tubing is ideal. Resin must be pulled to all corners of the laminate to achieve complete infusion. Due to the standard set-up of infusion where the infusion lines is in the middle of the laminate, the spiral tubing would usually be placed around the flanges. NOTE: Spiral tubing should always be wrapped in peel ply for ease of releasing. It is always useful to use sealant tape to stick in on corners for ease of use. Figure 8: Addition of vacuum lines to the layup. [10] 17

19 5.3 Vacuum bag Building of vacuum bag The vacuum bag should tight fitted around the entire mould, but still allow for plenty of room for materials, tubing networks etc. If the bag is too large it could result in resin pooling or if the bag is too small in improper infusion. Be very careful for making the cuts for the tubes through the bag, because it is usually these connections that spring leaks. NOTE: Clamp off the resin line before switching on the pump (Next step). This is necessary as the vacuum is drawn before the introduction of resin, and this will thus act as a temporary leakage if not sealed off Resin trap Figure 9: Vacuum bag built around the mould A key piece of equipment in VIP is the resin trap, as this prohibits the resin from entering the pump and thus not only can destroy the pump, but also cut of vacuum. A resin trap is a container, which is airtight, placed within the vacuum tubing circuit, between the pump and the laminate. The purpose of the resin trap is to catch any excess resin before it can enter and destroy the vacuum pump. [10] It is usual for resin to flow completely through portions of the laminate whilst still filling in dry spots in other parts. Due to this the resin frequently enters the vacuum line, while continuing to infuse. The resin trap will catch all these resin, while air is still allowed to flow back to the pump. Larger parts can have more than one resin trap if necessary, to ensure that if one resin trap is filled, it can just over flow into the other. NOTE: Ensure to wax the inside of the resin trap tank with mould release agent to ensure easy removal of cured resin. 18

20 5.4 Vacuum pump Attaching of the pump After all the components are in place the vacuum pump can be connected. It is in general a good idea to use a stronger pump than being used for vacuum bagging is necessary, as resin is being infused through the use of vacuum Ensure proper vacuum After the pump has been attached, ensure the resin flow line is clamped, and then it can be switched on. Air leaks, as in vacuum bagging, pose the biggest problems. VIP, unlike vacuum bagging, offers unlimited time to seek out the leaks, thus considerable effort can be made to find all the leaks. Expensive, but handy tools like, ultrasonic leak detectors, are available to aid in this process or a simple stethoscope could be used. It won t provide the precision of the ultrasonic detectors, but it will greatly amplify the leaks and provide economical helpful testing equipment. [10] 5.5 Prepare for infusion Selection of resin A common misconception in VIP is that the resin used to infuse is a special infusion resin. Although there are some resins that infuse easier/faster than others, any resin can actually be used, but the most influencing factor to consider is the viscosity. [10] Lower viscosity resins aids in infusion, as lower permeation of the reinforcements is allowed. Higher viscosity resin may also work, but it may require more careful planning of the amount of resin lines and flow media to be used Set-up of resin bucket Air entering the resin infusion line is a fatal flaw in VIP, thus the resin line should always be in contact with the resin in the bucket and under no circumstances be allowed to draw in any air. This can be achieved by buying specially made VIP buckets, which a pipe just connects to, or make it yourself. The tools include the bucket, a resin line holder, a resin flow line, some cable ties and spring clamp. The tube can be straightened on the resin line holder and kept in place by the cable ties, as illustrated in figure 25. The resin line holder can then be inserted into the bucket and clamped with the spring clamp or cable tied to the bucket at the top of the bucket. The resulting assembly should ensure that the resin line will stay in place and, if the resin is always kept at a level above the entrance of the tube, the line will never draw in air only resin. [10] 19

21 Figure 10: Resin line kept in place in bucket 5.6 Resin infusion Catalysing of resin and allowance for infusion Resin can be mixed once everything it setup. It is always good practise to double check that the resin flow line is firmly placed in the bucket full of resin and would not leave the system. The flow regulator (resin line clamp) can be removed and the resin should be sucked through the tube into the laminate. [10] The resin line will fill up quickly as the resin reaches the laminate. Once the resin line is full it will expand outward into the reinforcement. The infusion rate is dependent on various variables, but flow should be visible. Allow this to continue until the entire laminate is saturated or as advised in the VIP design. (Sometimes the resin is only infused up to the end of the flow mesh.) [10] Clamping of resin Once the laminate is wet out, there is no further need for resin entering. To prevent the air bubble from entering when the resin bucket is sucked dry, the resin line should be clamped off once the laminate is infused. NOTE: The clamping should be performed carefully as any significant force could potentially create a new leak. Once the infusion is complete, it does not mean the process is completed. The vacuum pump still needs to run until the laminate is cured or at least sufficiently gelled, otherwise premature air could be introduced. [10] 20

22 6 Testing 6.1 Test 1: core material infusion Problem statement Testing of the theoretical resin/core ratio of Lantor Sorric XF 2mm and 3mm core materials Testing of the flow rate through a core/glass laminate Testing of the test procedure for resin infusion Materials used 1. Lantor Sorric XF 2mm 2. Lantor Sorric XF 3mm 3. Fibre Glass Resin & Hardner: J & J Resin flow mesh 6. Release films 7. Resin flow channels 8. Vacuum pipes 9. Vacuum bagging film 10. Tacky tape Equipment used 1. Vacuum pump 2. Graphite solid flat mould Test monsters 1. Cut all the materials to size: 200mm x 100mm 2. Weigh all materials and document. 3. TEST MONSTERS: 21

23 TEST MONSTER LAY UP 1 Fibre Glass # Lantor Sorric XF 3mm Fibre Glass # Lantor Sorric XF 3mm Fibre Glass # Release film Resin flow mesh Vacuum bagging film 2 Lantor Sorric XF 3mm Release film Resin flow mesh Vacuum bagging film 3 Lantor Sorric XF 2mm Release film Resin flow mesh Vacuum bagging film Figure 11: Test monster layup 4. Do the setup as in Figure 2. Assure that the resin flow mesh to the vacuum port is big enough. Give each test monster its own resin flow channel & resin pipe 22

24 Let the first test monster s mesh stop about ¾ from the end. Seal the flow paths of between the test monsters by having a piece of tacky tape between the test monsters. = Vacuum port to pump ¼ of test Tacky tape Tacky tape Tacky tape Tacky tape Resin flow Resin pipe to Test procedure Figure 12: Testing layout 1. Clamp of the resin pipes before vacuum is applied. 2. Assure that vacuum is achieved 3. Put the resin pipe in the resin & slowly release the clamp. 4. Control the resin flow by applying more or less pressure on the clamp. 5. Let the resin run through to about ¾ from the end and choke the pipe again. 6. Leave the test monsters to vacuum infuse for about 24 hours. 7. Remove vacuum and demould parts. 23

25 6.1.6 Test results Material Weight before [g] Weight after [g] Absorbed resin calculated [g/m²] Actual resin absorbed [kg/m²] Test monster 1 (3x x3.4) = (0.6*36.6) + (2*28) = Test monster Test monster Mesh and peel ply Conclusions 1. The flow rate of the resin needs to be controlled by clamping of the resin pipe; resulting in the resin flowing slowly through the mesh, not bulking at the beginning and producing a good impregnated laminate. 2. The mesh needs to stop about ¾ from the end of the laminate as to slow down the flow rate of the resin & impregnating the laminate thoroughly. 3. There needs to be a big flow path to the vacuum pipe. This let all the resin being sucked through the whole laminate, whilst not blocking the vacuum pipe; Resulting in a laminate with the minimum ratio of resin. 4. All the resin needs to be calculated preceding the infusion; this includes the resin in the: Laminate materials The resin flow channel The pipe The excess in the mesh 5. The practical resin to laminate/core material ratio was less than calculated. This could be an indication that the resin infusion process tested was successful. 6.2 Test 2: Resin infusion of flap 2 mould Materials used Mould area = 2 x 0.4 =0.8m Industrial Fibre glass (x2) 12. Lantor Sorric XF 3mm (x2) 13. Fibre Glass

26 14. Resin & Hardner: J & J (3.5kg) 15. Resin flow mesh 16. Release films 17. Resin flow channels 18. Vacuum pipes 19. Vacuum bagging film 20. Tacky tape Equipment used 3. Vacuum pump 4. Flap mould 2 kg/m^2 or m^2 Convert to kg Mesh 0.64 Resin uptake 0.64 Channel l = 0.001m^ Core kg/m^ Glass % of weight Pipe E-05 1l = 0.001m^ AREA 0.8 TOTAL (kg)

27 6.2.3 Results The following pictures were derived from the experiment: a) b) Figure 13: Cover all pointy/sharp edges with felt. a) b) Figure 14: Make ±160mm flange on mould for release film to lie on. Make sure the bag is big enough to vacuum into all edges. a) b) Figure 15: Determine where vacuum ports should be and make sure that flow lines of Lantor sorric core material coincides with flow of resin. Situated vacuum ports on corners 26

28 a) b) Figure 16: The cable ties ensure that pipe doesn t get sucked into vacuum chamber and the tacky tape seals it off. Make a resin dump in a vacuum chamber & put some felt around the pipe exits to suck in resin and reduce spraying of resin. a) b) Figure 17: Resin bucket and tape it down on a table with tacky tape near port, so you don t need to hold it. a) b) Figure 18: Lift resin flow channel a little bit to the top with the mesh a bit under it in, so that it doesn t sit on laminate. 27

29 a) b) c) Figure 19: The mesh can stop at end of the horizontal plane and then the resin can slowing catch up to the end of the vertical plane Conclusion This experiment was successful and the produced mould had little finishing needed. It was noted that the setup took longer than expected and it could therefore be concluded that resin infusion is time consuming for smaller moulds. On larger moulds and parts the process would be winning time, but any mould or part smaller than two square meters it is better to use hand-layup with vacuum bagging. 7 Conclusion It was stated that a flap-2 moulds for the JS1 needed to be built and the possibility of using vacuum infusion needed to be investigated and tested. The investigation showed good results regarding the flow of resin and the using of core material. The flap was built and it could be overall concluded that vacuum infusion gives good results regarding weight reduction, but is time consuming for smaller moulds. 28