A carefully controlled, robust mass production process provides manufacturers of Class IV LPG/CNG storage tanks with a way to meet the growing demand in Europe and Asia.
Mass production without sacrificing quality: MIKROSAM (Prilep, Macedonia) has taken advantage of the European and Asian demand for LPG and CNG pressure vessels by building an automated production facility for container production. An example is this LPG tank plant, which has two complete mirrored production lines, side by side, each capable of winding five containers simultaneously, and equipped with a continuous curing oven.
Also wrapped with carbon fiber. MIKROSAM has produced 20-30 automated filament winding lines and more stand-alone winding machines, including this machine for the production of carbon fiber reinforced IV CNG tanks.
Step 1: Each line is designed using Autodesk software. This plant design actually has two complete lines, the one on the right is a mirror image of the left. Each is capable of winding five containers simultaneously and features a continuous rather than batch curing oven.
Step 2: The first module in the line (not shown here) blow molds the thermoplastic liner on a metal mandrel, which is then loaded onto a square turntable, five on each side, like the one in the foreground right of this photo that.
Step 3: The robotic arm picks up 5 pads at a time from the turntable on the left and prepares to transfer them to the winding module.
Step 4: Here, the robot installs five liners in the filament winding module of the leftmost line. Each bushing shaft used as a winding spindle is inserted into the jig.
Step 6: The fibers are then impregnated with resin in a resin bath and automatically drawn down, eliminating the risk of dripping.
Step 7: Tanks are filament wound. The fully automatic filament winding system features automatic cut and restart with precise resin control and simultaneously winds each of the five liners in approximately 5-7 minutes.
Step 8: The wound cans are then placed on an automatic conveyor belt into the curing chamber.
Step 9: The cans are cured for 2-3 hours at temperatures ranging from 60° to 120°C, depending on the resin used for the product wound on this factory line.
Step 10: After curing, the tank receives a UV resistant coating and is pressure tested. The tank exceeded the burst test limit of 70 bar, failing at 110 bar and the desired mode, between the cylindrical centerline and the dome.
Finished products for fast-growing markets. Manufactured on another MIKROSAM highly automated production line at Supreme Industries (Halore, Gujarat, India) ensures high yield and high quality of these KAVACH Composite Type IV LPG cylinders.
High-pressure gas storage tanks are one of the largest and fastest-growing markets for advanced composites (read Chris Red’s composite tank market assessment in “Alternative Fuel Pressure Vessels, 2014-2023,” Editor’s Picks, top right bottom). Most are used to store and transport liquid propane gas (LPG) and compressed natural gas (CNG). In an October 2015 report, market research firm Lucintel (Irvine, TX, USA) predicted that due to increased demand for CNG-powered vehicles and the need for lighter weight but greater gas capacity than traditional steel containers of gas cylinders. The continued global push to reduce carbon emissions is driving parallel growth of LPG not only as a transportation fuel, but also as a clean cooking fuel, driven by government initiatives in India, Indonesia, China and Africa.
Europe is the largest growth market for CNG storage tanks; Asia has the largest demand for LPG tanks. Therefore, MIKROSAM (Prilep, Macedonia), a provider of composite manufacturing solutions located between these two regions, has capitalized on this trend by offering an automated production line for LPG and CNG composite tanks that can run three daily shifts with annual production As many as 500,000 LPG tanks with only four operators participating. MIKROSAM recently designed and built the largest production line of its kind in the world to date for a client in India, giving us a glimpse into the world of automated composite manufacturing. Such systems reveal both the challenges that must be overcome and the opportunities facing the entire pressure vessel industry.
Although MIKROSAM has been manufacturing filament winding and prepreg equipment for 20 years and has been manufacturing automated fiber placement and tape laying systems since 2007, its workforce is comparable to that of Silicon Valley. The average employee age is 30; 50% are engineers, and 10-15% have a PhD or an engineering MBA, the latter being the norm for European technology companies.
MIKROSAM has the ability to produce equipment for various composite manufacturing processes under one roof, and specializes in filament winding technology, having produced 30 fully automatic systems, but many more individual winding modules.
“In the past five years, we’ve seen more inquiries about automated or semi-automated systems,” said sales manager Dimitar Bogdanoski.“Most of our innovations in filament winding have been in automated processes that were previously done manually, such as automatic cutting and restarting of fiber reinforcements once winding is complete.” Automated resin mixing and filling is also now commonplace, the automatic loading and unloading of plastic liners in the production of tanks, and the automatic loading and unloading of filament winding mandrels used in the production of drums, drive shafts and composite isolators.
Another key component is the central control system, which MIKROSAM calls TCON. It manages all modules in an integrated production line from one location, while recording all important parameters such as resin, oven and production ambient temperature and humidity, fiber and resin type, operator name and date and time of production start and stop, etc.
“Each tank has individual passport data, which is its unique written record,” Bogdanoski observed. Quality and traceability are really important as these lines are used for Type IV tanks and are made of carbon and/or fiberglass filaments wound on a plastic liner, the composite material carrying all the structural loads. They weigh less than Types I, II, and III, but are also the most expensive (read more about pressure vessel tank “type” names online in “CNG Tanks: Pressure Vessel Epicenter” under Editor’s Picks in the upper right corner). more information).Importantly, automated equipment that produces products exactly as designed, and it has the ability to upgrade in the future and generate big data, is now considered a prerequisite for Industry 4.0 and IoT (CW) manufacturing productivity Guest Columnist Bob Griffiths Observing the emerging impact of Industry 4.0 in the CFK-Valley Stade Convention 2015 Report, CW Guest Columnist Avner Ben-Bassat advocates online under Editor’s Picks at the top for “Applying IoT to Composites Production Efficiency” ).
Every automated filament winding line begins with close discussions between MIKROSAM and its customers. Together, they determine the target tank size, the definition of the fibers and resins that will be used, the level of automation required, and the criteria to which the tank will be certified. MIKROSAM then used Autodesk software (Autodesk Inc., San Rafael, CA, US) to design the production line and its various modules.
After the customer approves the final design, production begins. “Some of the modules and parts are made by us, some are off-the-shelf, and some are subcontracted by us,” explains Bogdanoski. But the point is to control capital investment by not “reinventing the wheel.” “For example, we buy robots and motors from well-known suppliers. Our strategy is to provide the highest quality and the most affordable cost for each system design.”
At the same time, MIKROSAM developed the control software and data acquisition system. “Then we assemble all the units and integrate the control system into our Macedonia plant,” Bogdanoski said. “We set up complete lines to produce parts using the exact fibers and resins to be used, so customers can see the line in action, inspect it and discuss any issues,” he added. After approval by the customer, the production line is disassembled and shipped to the customer’s site for reassembly.
The design and pre-acceptance construction takes approximately 12 months, followed by 1 to 2 months for the MIKROSAM team to complete the installation at the customer site. “Then we go to pilot production,” Bogdanoski said, “and stay to help with the start-up, including training operations and maintenance personnel.”
MIKROSAM provides continuous support through a remote maintenance system. “Customers connect the production line to us via the Internet,” Bogdanoski explained, “and our people then maintain the line software and control systems, providing any updates that are available.” This is normal in European factories, he notes. MIKROSAM provides customers with software updates free of charge during the entire life cycle of automated manufacturing systems.
Presented here are the functional results of the plant design (step 1 photo, left) for the production of LPG tanks, which requires two complete production lines side by side. The one on the right is a mirror image of the one on the left. Each is capable of winding five containers simultaneously and features a continuous rather than batch curing oven. The first module of each automated composite LPG tank production line blows plastic liners. Since MIKROSAM does not manufacture plastic blow Moulding equipment, it cooperates with a German manufacturer to produce these modules. On each line, can liners be loaded onto a rotating four-sided conveyor belt from which robotic arms pick up five liners at a time, onto which shafts have been welded for handling and winding (step 2).
The robotic arm then moves the liner into an automated filament winding module designed and manufactured by MIKROSAM (step 3).Insert each bushing shaft used as a winding spindle into the jig (step 4).Once all five shafts are inserted, the liner is ready to start winding. Fiberglass yarn for winding is pulled from multiple creels (step 5).The line uses a relatively simple creel system, but closed creels with mechanical or electronic tension control are also available. The computer-controlled electronic system is the most precise, providing servo-controlled tension to each fiber.
The yarn is then pulled into a dipper with a resin bath (step 6).”We have very good control over resin content,” Bogdanoski points out. This is achieved by precisely adjusting the doctor blade, which regulates the delivery of the resin on the fibers: “Without dripping, the customer saves a lot of money, not only in resin savings, but also in tank surface treatment and equipment maintenance.” MIKROSAM There is also a patented automatic cut and restart feature, so no time or labor costs are wasted between the end of packing one set of cans and the start of packing the next.
Winding typically takes 5-7 minutes, depending on the size of the LPG tank (step 7).After winding is complete, the line’s robotic arm removes a set of five winding cans and places them into the automatic monorail conveyor system (step 8).The cans are then moved into the curing chamber of the line and the composite cans are cured at 60-120°C depending on the type of resin used (step 9).
Curing ovens can be equipped with gas or electric heaters according to customer specifications. Standard resins used in LPG tanks require 2-3 hours to cure at these temperatures. For CNG tanks, the resin varies and typically cures within 3-4 hours, but can sometimes take up to 10 hours to cure. “All of this is driven by canister design,” Bogdanoski explained, noting that “we design the curing oven based on the range of resin systems the customer wants to use.” Canisters can cure faster at higher temperatures, but This would exceed the limit of plastic linings.
After curing, the canister is robotically removed and placed into another chamber where, according to some industry standards, a coating is applied to protect against ultraviolet (UV) radiation, which is some type of liquefied petroleum gas tank required. UV coating modules can be automatic or manual. In LPG lines, they are semi-automated: the tanks are rotated by machines, while the coating is applied manually by technicians. Once the coating dries, the shaft used to connect the tank to the filament winding machine is removed; the tank is machine-advanced, but each shaft is removed manually, using a gun-like tool to quickly unscrew the shaft and remove it Boxed for reuse. The tanks then go into a single test station, shared by both production lines, where each tank must be hydrostatically tested for its working pressure according to this customer’s specification (step 10).
The test station for the plant’s LPG production line is semi-automated – 5-10 tanks are manually placed into the test cell, but subsequent testing is done automatically. In other production lines made by MIKROSAM, the test station is fully automated. The robotic arm places 5-10 tanks into the test bench and then removes them after completing the hydrostatic test and evaluating the results. Since this part of all MIKROSAM automated composite tank production lines contain proprietary technology, it is not shown in the photos of the manufacturing steps below. However, it did end this largest LPG compound tank operation. Test tanks are manually removed from the test station, equipped with valves and lids, and ready for shipment.
Although this two-line production line is not the most automated system ever produced by MIKROSAM, it still represents a major achievement. Bogdanoski noted that customers opted to semi-automate the final station of each production line in order to provide some employment opportunities for technicians, while automating as much as possible to ensure quality. The challenge lies in requiring many different products to be produced on one production line. “For many of our projects,” he said, “customers want to produce tanks of different sizes, while changing lengths and diameters. So, we had to adapt all the modules to that change.” While for this LPG line, just changing length, but for the CNG tank line currently under construction, the customer wants to produce several batches of 200-mm diameter and 1-meter-long tanks, and then immediately switch to producing 400-mm diameter and 600-mm long tanks. The production line must be able to do this automatically, adjusting all modules in the system to accommodate the change, Bogdanoski said. “As a result, not only did new winding programs have to be generated, but the processing units and curing ovens also had to be adapted to the new dimensions. This was one of the most difficult requirements to meet, but we managed to make it happen.”
Scheduled for customer review this month, MIKROSAM’s newest tank production line is fully automated and will reportedly produce 50,000 Type IV composite CNG tanks per year.
“This is the only product of its kind in the world,” Bogdanoski claims, adding that once approved, it will be delivered to one of Europe’s top automakers. The annual yield is actually quite high. LPG tanks typically operate at 20 bar, but CNG tanks operate at much higher pressures (to 250 bar) and therefore require longer winding times.
MIKROSAM is also designing a combined production line that will contain the largest automated LPG and CNG tank manufacturing system in one location. “This market is now very interested in alternative fuels to diesel,” Bogdanoski observes, “so filament wound composite tanks for natural gas and hydrogen are gaining popularity, and automation is key to delivering the required quality and cost.”
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Post time: Apr-25-2022