Correct mold maintenance: a must! | Composite World

CT will investigate the mold care product suppliers to guide the critical steps of mold preparation and maintenance. #Marketing#regulation
The clean and easy release of parts depends on the correct use of sealants and release agents, followed by strict and strict maintenance practices. Source: Specialty Products Company
Solvent-based mold release agents have been used safely by composite material processors for decades because safety regulations require mold care technicians to wear appropriate safety equipment (masks and gloves) during product application. Source: Specialty Products Company
The demand for water-based release agents is greater, especially when the molder is far away from the volatile organic compounds in the workshop. Some water-based mold release agents have the same curing and mold release properties as solvent-based mold release agents. Source: Specialty Products Company
Polishes, sealants and release agents can only be applied with clean cotton towels or high-quality paper towels. Discard paper towels after use. The cotton towel should be reduced to a non-release state after use to prevent the next mold from being contaminated by the cured or partially cured release agent. Source: Henkel Corporation.
When using a paste wax release agent, please start with a clean mold, then sand, compound, seal and demold. The following four images show the gradual improvement of the tool surface after each step. Here, the gel coat surface after sanding (magnification 1000 times) is shown. The uneven surface shows some defects, if there is no sealant and release agent, the part can be fixed in the mold. Source: TR Industries
Here, the gel coat after polishing (10,000 times magnification) is shown. Polishing agent can remove fine scratches caused by grinding. Source: TR Industries
In this image, the gel coat can be seen after sealing (magnification 1,000 times). The sealant fills the remaining scratches and provides a surface on which the paste wax is applied. Source: TR Industries
Finally, after waxing (10,000 times magnification), the gel coat was revealed. The wax should be polished by hand to achieve the final high gloss and provide effective release performance. Source: TR Industries
Although many products (CAD/CAM software, machining centers, molding machines and finishing equipment) used in manufacturing by composite materials processors are essential for producing high-quality parts, it can be said that there is nothing more important than molds. . The tool surface sets the quality baseline for the quality of the produced parts, so the shape and surface quality of the parts will not be better than the quality and baseline of the tool. Most processors can intuitively understand this “quality tool = quality part” equation. What is not well understood is the critical need to maintain this baseline through proper mold maintenance. Well-maintained tools will keep the quality of the production line longer and produce more and always acceptable parts. The irony is that many processors see the cost and time required for mold preparation as an obstacle to productivity when faced with tight deadlines. Then, the negative effects of poor mold care will slowly accumulate and only become apparent when it is too late to facilitate remediation. The corners of the mold preparation aggravate the inconsistency of the product, shorten the service life of the tool, and may cause expensive and time-consuming rework of the final product. The apparent increase in production speed was offset by the cost of remedial measures.
The mold care industry is full of products designed to help processors easily meet every mold maintenance need. Mold care products can generally be divided into five categories: mold compounds, mold sealants, mold release agents, mold polishes, and mold cleaners. However, these products are most effective when used correctly, and for some processors, it is easier said than done.
The fastest growing product is an external release agent, which is applied to the mold surface to prevent contact or adhesion between the mold and the part. The mold release agent for traditional composite molded products (open mold and closed mold) was initially provided in the form of a paste wax. Wax needs to be used after each cycle and is therefore marked as a “victim” because the wax is consumed by every part of the molding. Ray Lukich, sales manager of TR Industries (South Gate, California), is a supplier of pasty waxes and Multi-Pull series semi-permanent release agents. He said that depending on the complexity of the resin and parts, some waxes can last up to Three cycles, but he pointed out that the shortcomings still exist: waxing takes time and effort.
The labor-intensive wax system has prompted people to demand a longer-life demolding system. The answer has been around for more than 50 years. It is a semi-permanent release agent. The release agent usually has a solvent-based carrier and can be effectively released in multiple cycles-the number of cycles depends on the resin, fiber and tool material used. The number of releases for each application varies from a few to hundreds.
Semi-permanent mold release agents are attractive to high-volume molders because they do not require frequent application and cure relatively quickly. The function of semi-permanent materials mainly depends on the polymer crosslinked and bonded with the substrate, which is usually a mold sealant.
However, the semi-permanent problem is the solvent carrier. Many processors try to get rid of workshop solvents. Therefore, mold care suppliers have been working on developing water-based semi-permanent mold release agents in the past few years. Peter Heidecker, Asia Pacific Manager of Zyvax (Ellijay, Georgia), announced the release of EnviroShield, FiberglassShield, WaterShield and Flex-Z anti-sticking agents. He said: “In some countries, this is due to concerns about worker safety or government regulations.” “In other cases, the transportation costs of volatile/hazardous substances have become more and more expensive.”
The use of water-based releases also provides an opportunity to eliminate hazardous waste removal costs.
Loren Nauss, Maintenance Chemicals Technical Manager at Henkel Corporation (Rocky Hills, Connecticut), which manufactures the Frekote series of mold care products, noted that there is an increasing demand from governments and customers to remove VOCs from the workplace. Nauss said: “The VOC and HAP (hazardous air pollutants) content of all materials used in the composite manufacturing process, and even processing aids such as mold release agents, have always been a concern for processors,” Nauss said. This is largely due to the trend of increasingly stringent regulations, such as the Maximum Achievable Control Technology (MACT) standard for composite manufacturing in the United States. “This trend requires mold care product manufacturers to research alternative solvents and develop water, cleaners, sealants and mold release agents.” Nauss said.
But water-based release initially posed challenges. They require longer curing times (the water takes longer to evaporate) than solvent-based systems, and they do not have as many release cycles as solvent-based systems. Nevertheless, the desire to exclude VOCs from the production environment still exists, and mold care product manufacturers have been working hard to develop water-based mold release agents to replace solvent-based systems. Although water-based emissions are available from many suppliers, the prospects are clearly mixed.
Zyvax has been active in the field of water-based products with its EnviroShield products, and has reported curing and demolding capabilities comparable to solvent-based products-15 minutes between two coatings and 30 minutes before molding, while solvent-based Flex has two steps It takes 15 minutes each-Z Zyvax North America Sales Manager Tannis Layman said: “In 2010, 70% of our global sales came from environmentally friendly products. I am very happy about this.”
Other suppliers report that water-based release is still gaining a foothold in the release market. Nancy Teufel, product manager of mold care product manufacturer AXEL Plastics Research Labs Inc. (located in Woodside, New York), said: “We pay more for water-based release agents for lipstick services than they actually are. Conversion. It will grow, but in high volume In the market, there is no patience.”
Mark Finn, vice president of sales and marketing at McLube (Aston, Pennsylvania), says that water-based systems are in demand, but not always feasible. He said: “Most of our customers want to use green technology products.” He said: “When possible, “we work closely with compound molders to help them convert solvent-based materials into our water-based products. . “However, the customer’s current process, production requirements, or costs associated with modifying their processes may make this move impractical or costly.
Obviously, the safety provided by water-based systems means that they will continue to exist and will likely continue to develop into the demolding standard for composite processing machines.
Developing new composite parts or structures can be time consuming. When the mold is completed, it is understandable to rush to produce parts, turn losses into profits and complete before the deadline. However, molds with improper surface preparation have not yet been produced. The time and effort required for proper mold preparation can pay for itself by extending tool life and improving part quality.
An immediate consideration is that proper mold preparation should be carried out before using mold care products. Compared with production tools, how much time should it take to perfect the master mold or plug? The experts contacted for this article suggest that any time spent repairing and fine-tuning the mainframe or plug is spent on money and energy. “It’s best to have a perfect plug to minimize part rework,” said Robert Renshaw, managing director of REXCO (Conyers, Georgia), which produces five products, PARTALL and FORMULA. . “Do all repairs and sanding on the stopper instead of the production mold. Once you start sanding the mold, this is the beginning of the end of the mold.”
Experts say that the way the mold is prepared depends on several variables, including the molding process, tool material, tool geometry, process temperature, cycle time, part size, and required part surface quality. Most mold care product suppliers provide questionnaires or worksheets to help guide customers through the product selection process to help optimize mold release performance.
McLube’s Finn said that composite tools with a tool gel-coated outer layer are common in opening, closing and closing systems, but they are sometimes difficult to prepare and maintain. Finn reports: “Non-metal molds are one of the more challenging surfaces that require care.” “They may be difficult to wet, which can cause a good demolding product to not work properly. This is why it is necessary to work closely with production To identify specific issue issues.”
Metal tools can be sealed and ready to be released, but they tend to be more porous and have different temperature requirements. In any case, depending on the type of release agent, the mold preparation process has some basic guidelines.
Cleanliness is crucial. Every supplier contacted with this story first explained the importance of cleaning the mold surface before using sealants, mold release agents or any other mold care products. “Our main concern is to maintain a clean environment in the workplace,” McLub’s Finn said. “This applies to cleaning molds, cleaning tools, and cleaning release coating applications. For manufacturers, it is important to understand that the absence of a release coating will make dirty molds work effectively.”
Henkel’s Nauss recommends: “Before using mold sealants and mold release agents, please ensure that the mold is properly cleaned. Improper use of cleaning agents will cause product performance degradation. In addition, please be careful not to overuse mold release agents. This will cause mold Accumulate and cause discoloration and performance degradation.”
A clean surface is a surface free of dust, sealants, emissions, polymers or other contaminants. Cleaning should be done with a clean lint-free cotton cloth. Some suppliers also recommend the use of high-quality paper towels. Mold cleaner should not be mixed with other cleaners or mold care products. All mold care products should be stored in airtight containers at room temperature.
Semi-permanent release. The first step of semi-permanent mold preparation is optional. It is the application of polishing agent to make the mold surface smooth and uniform. Then force the use of mold sealants-sometimes called interfacial coatings. The number of mold sealant coatings required varies depending on the type of mold and release agent, but it can range from one to several. This step is critical because the sealant fills the small gaps, pits and any other irregularities in the mold to provide a smooth surface to which the release agent can adhere. In addition, molds that have mold release but no sealant will have microcracks. Win Doolittle, a manufacturer of KantStik series of solvent-based and water-based mold release agents, and business director of Specialty Products (Corona, California) pointed out that the sealant forms a barrier between the tool surface and the molding material and prevents styrene from the mold surface migrate. Pasting composite parts on the tool surface may cause fogging that is difficult to clean.
In addition, Heidecker of Zyvax said: “The correct seal will help improve mold release, make molds have a longer life, and reduce the use of mold release agents.” He pointed out that too many molders have become The “more is better” rule. “Of course, people think that applying more mold release can avoid the need to seal the mold.”
Teufel of Axel says that this temptation is easy to take shortcuts and avoid using the sealer entirely. “Customers think that the sealer and the releaser are the same, so they added an extra release without a sealer.” And even if the sealant is used, many suppliers also say that the more important issue is to allow enough time to apply Thorough curing between layers. Teufel says that drying does not cure, and points out that less cured coatings are better than many uncured coatings.
After the sealant is fully cured, the next step is to apply a release agent. It is usually wiped, and like a sealant, one or more coatings may be required, depending on the geometry of the tool. Likewise, especially for semi-permanent release agents, time must be allowed for the complete curing between the two layers. Solvent-based release agents may take 10 to 30 minutes to cure-the longer the better.
During the molding process, the operator will be required to reapply the release agent to maintain the desired release performance. How many versions can be implemented for different applications. Henkel’s Nauss said: “Many customers ask,’How many versions can I get from this product?” “This is one of the biggest misconceptions about semi-permanent release agents. Before use in production, every application must go through Identification. Part materials, temperature, geometry, etc. are all important considerations when choosing a suitable release agent.”
Dewaxing. When using a dewaxing agent, only slight changes are required. First, the mold must be sanded with gradually finer sandpaper. TR’s Lukich said that it can grind fine powder from 600 to 1200 into paper. Doolittle of Specialty Products says that depending on the gloss required, 2,000 grit can be guaranteed. Next is the application of tool compound to remove fine scratches left by fine grit. Doolittle said that for composite applications, at least a 2,400-rpm buffer should be used and hope to cover 1 square foot every 20 seconds. After mixing, two coats of sealant should be applied and sanded by hand to high gloss. After the wax is released, it is also hand-applied and hand-polished. Doolittle said that six layers of wax paste are not uncommon, with 20 minutes to an hour between each layer to cure, and the last layer to cure overnight.
Tape test. Regardless of whether the release agent is semi-permanent or waxy, the final step of the mold preparation process is to use high-quality tape to test randomly selected mold surface locations to verify complete coverage of the sealant, release agent and polish. Stick the tape and peel it off the surface. The peel resistance should be significantly lower than the peel resistance on the unprepared mold. Areas with significant peel resistance should be resealed, and then a release agent should be used.
All in all, cleaning, polishing, sealing and releasing applications can consume the entire work shift. Although this is a bit excessive, mold preparation should be regarded as the last critical step in the mold manufacturing process. When it becomes a habit rather than an exception, the final tool should produce the best possible parts and structure. The mold release and curing can be accelerated by using an oven, or Renshaw suggests, the operator can adjust multiple molds at the same time to maximize efficiency. Zyvax’s technical sales representative Drew Martin reports that many customers’ complaints about product performance can be attributed to improper use of the product: “That’s why we evaluate the customer’s process, mold conditions (and) current procedures and make recommendations. Reason. Improve their overall performance. Generally, we find that the most common areas of improvement are product selection and application.”
However, using the right product is only half the battle. Everyone who came into contact with the story pointed out that the most effective, efficient and well-functioning composites workshop they have ever seen has one thing in common: a clear, structured, and measurable mold maintenance plan for regular removal from production The mold is cleaned, refurbished, recoated with sealant and released, and re-polished.
Each mold has a timetable to ensure that it is removed from production after a predetermined number of cycles. Timing tightening is to prevent problems (for example, parts sticking, fogging, cracking), not to respond to problems. This requires trial and error to determine when a particular part or mold begins to show signs of adhesion and fogging. Lukich said: “The fact is that after the smog is formed, when cleaning tools becomes more difficult, many shops will eventually encounter problems.” Doolittle agreed: “Spend your energy on solving mold problems, not parts workarounds. on.”
Given its importance, mold maintenance in some stores is only entrusted to well-trained and experienced employees. Teufel said: “Mold cleaning and maintenance are usually handed over to the person hired last.” Zyvax’s Heidecker said: “Usually, the operator with the least training will be the person in charge of mold maintenance/maintenance.” He recommends having experienced employees. Understand the importance of mold maintenance and take the responsibility.
Zyvax technical sales representative Michael Mapes recommends the following progressive mold maintenance plan: Preventive measures: check every time the part is pulled out and put back into production: every X number of cycles or every X days. Smaller maintenance: one coat each The main maintenance of the release agent X cycles: every X cycles, strip the tool, clean the tool, and then recoat the sealing machine and release
First, the molder can develop a simple paper-based mold tracking system that records the following basic parameters: mold number, number of parts and pulls, cleaning cycle date, sealant used, number of sealant coatings, sealant Application date, release time used, number of release layers and release date.
Teufel pointed out that when using a closed mold, the B side of the mold may ultimately determine the cleaning schedule. “Side B is usually poorly machined and porous, so parts tend to stick here first.” She also said to pay attention to resins because more aggressive polymers can erode the mold surface faster than non-aggressive materials. Finally, she recommends regular inspections for chronic wear marks on finished parts. Scratches indicate the areas where the part wears the fastest, which is caused by the angle at which the part was removed or the sharp angle of the geometry of the tool binding the part. These areas determine the maintenance plan.
After repairing the mold, the tape peel test should be repeated. If any part of the tool is repaired with a patched matte, Teufel says that additional sealant should be used and released in that area, because matte tends to be abnormally porous.
Mold preparation and mold maintenance schedules not only bring technical challenges, but also cultural challenges. Several interviewees pointed out that it is not uncommon for a store to have entrenched bad mold maintenance habits, and employees believe their knowledge of mold maintenance products and processes is impeccable. TR’s Lukich said: “The habits of some stores are difficult to control and change.” “They tend to go back to their original habits.” Rexco’s Renshaw pointed out: “Good record keeping ability can make a good store with weaker operating capabilities. Different companies.”
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Post time: Dec-23-2020
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