Mold cleaning is a process where major maintenance bottlenecks often occur because molds are pulled faster than they can be cleaned and made production-ready. I have visited plants where molds waiting to be cleaned line hallways and toolrooms, taking up valuable bench space.
Many times, in order to meet production demands, molds get reset dirty or the cleaning process is rushed, which subjects tooling to more damage through hurried handling. The question is asked, “Can we run it the way it is, or does it really need to be cleaned?” In companies where firefighting is the accepted culture, the mold will be reset and started; if all the parts come out clean, it runs. Once this happens a few times, management comes to assume that molds need to be cleaned only when the residue level is bad enough to migrate out onto the part, or until the mold locks (galls) up.
Some shops handle cleaning chores by enlisting non-skilled employees or toolroom apprentices to wash tooling and plates as quickly as the repair technician can take them apart. This practice works, unless the product has critical flash, dimensional or aesthetic specifications, or the mold has a history of maintenance, reliability or quality issues. It is difficult for the repair technician to accurate troubleshoot mold and part defects when all the track marks are washed off from the tooling and plates.
Why clean injection molds?
Injection molding is a widely used process in mass production, therefore it is essential that the process is flawless in order to avoid unnecessary costs incurred from having to redo results or repair and or replace equipment and to ensure the quality of a large number of pieces.
Proper lubrication of the mold extraction mechanisms or mold cooling channels free from limescale and rust accumulations, are elements to pay attention to in the maintenance of injection molding machines. But the perfect cleanliness of the mould figures is perhaps the most important factor to ensure the highest quality of production.
It’s easy for a small imperfection in the surface of the mold, in contact with the molten polymer material, to create a defect in the final part once it has cooled. For this reason it is essential to rely on cleaning systems that not only carefully remove the residues that can be deposited on the mould figures (especially the smallest and richest ones), but also in order to prevent any damage to the mold.
The residues to be removed are usually deposits of release agents and lubricating oils – used to allow the detachment of the artifacts from the walls of the molds and the correct sliding of the mobile part of the mould. In addition, it is also possible that the molds must be cleaned of residues left by the gases that are created in the presence of pressure and high temperatures
How to clean injection molds
In order to avoid any damage to the surface of the mold, operations such as sandblasting, the small “clothespins” used to clean the surface of the mould or the use of aggressive and potentially corrosive substances are absolutely to be avoided as they could be counterproductive.
Even resorting to manual washing processes with rags and solvents may not be the best solution, as it could lead to unsatisfactory cleaning standards, especially in the case of moulds with complex geometries and small figures.
Finally, given the considerable impact of a mold on the quality of mass production, it would be advisable to proceed with a standardized washing process that always uses the same products: in this way it will be possible to minimize the possible variability of the production parts due to the level of cleanliness of the mold, eliminating the human factor from the equation.
Automatic parts washers that use gentle water-based detergents are almost always the best choice for washing injection molds.
In the case of complex moulds and with very small parts it may be necessary to resort to ultrasonic cleaning technology that allows you to reach every millimetre of the mold surface effectively. Ultrasonic cleaners have special features that generate micro-explosions in the washing fluid that the mold is immersed in. These in turn create friction that enhances the cleaning effect of the fluid, even when dealing with fine surface details.
For simpler moulds, however, a rotating basket parts washing machine can be sufficient to ensure standardization, effectiveness and delicacy of washing.
The only exceptions are hot chamber molds and mirror-polished molds.
Injection molding equipment is the backbone of many manufacturing operations, enabling the production of a wide range of plastic products efficiently and cost-effectively. However, like any machinery, injection molding equipment requires regular maintenance to ensure optimal performance, longevity, and safety. In this blog post, we’ll explore some essential maintenance tips to keep your injection molding equipment running smoothly and prevent costly downtime.
1. Regular Inspection
Regular inspections are key to identifying potential issues early on and preventing them from escalating into more significant problems. Schedule routine inspections of your injection molding equipment to check for signs of wear and tear, loose connections, leaks, and other issues that may affect performance. Pay close attention to critical components such as screws, barrels, nozzles, and hydraulic systems.
2. Lubrication
Proper lubrication is essential for ensuring smooth operation and preventing friction-related damage. Refer to the manufacturer’s guidelines to determine the appropriate lubricants and lubrication intervals for different components of your injection molding equipment. Over-lubrication can be as detrimental as under-lubrication, so follow the recommended guidelines carefully to avoid excess buildup and contamination.
3. Cleanliness
Maintaining cleanliness is crucial for preventing contamination and ensuring the quality of molded products. Regularly clean the surfaces, molds, and components of your injection molding equipment using suitable cleaning agents and techniques. Pay particular attention to areas prone to buildup, such as cooling channels, ejector pins, and vents. Implementing a comprehensive cleaning regimen will help prolong the lifespan of your equipment and minimize the risk of defects.
4. Temperature Control
Maintaining precise temperature control is essential for achieving consistent molding results and preventing thermal degradation of materials. Calibrate and monitor the temperature settings of heating elements, molds, and cooling systems regularly to ensure they are operating within the specified range. Periodically inspect and clean heating elements, thermocouples, and temperature sensors to maintain accuracy and reliability.
5. Replace Worn Components
Over time, components of injection molding equipment may wear out or become damaged due to prolonged use. Keep an inventory of spare parts and regularly replace worn or damaged components to prevent unexpected breakdowns and downtime. Components such as seals, O-rings, nozzles, and heating elements should be replaced as part of routine maintenance to ensure optimal performance and reliability.
6. Operator Training
Invest in comprehensive training programs for operators and maintenance personnel to ensure they understand the proper operation and maintenance procedures for injection molding equipment. Empower your team with the knowledge and skills they need to identify potential issues, perform routine maintenance tasks, and troubleshoot common problems effectively. Regular training sessions will help instill a culture of safety, efficiency, and accountability within your organization.
By following these maintenance tips diligently, you can extend the lifespan of your injection molding equipment, minimize downtime, and maximize productivity. Remember that proactive maintenance is always more cost-effective than reactive repairs, so prioritize regular inspections and preventive maintenance tasks. With proper care and attention, your injection molding equipment will continue to deliver high-quality results and contribute to the success of your manufacturing operations.
Injection moulding is a widely used process in mass production, therefore it is essential that the process is flawless in order to avoid unnecessary costs incurred from having to redo results or repair and or replace equipment and to ensure the quality of a large number of pieces.
Proper lubrication of the mould extraction mechanisms or mould cooling channels free from limescale and rust accumulations, are elements to pay attention to in the maintenance of injection moulding machines. But the perfect cleanliness of the mould figures is perhaps the most important factor to ensure the highest quality of production.
It’s easy for a small imperfection in the surface of the mould, in contact with the molten polymer material, to create a defect in the final part once it has cooled. For this reason it is essential to rely on cleaning systems that not only carefully remove the residues that can be deposited on the mould figures (especially the smallest and richest ones), but also in order to prevent any damage to the mould.
There are five primary cleaning methods to consider:
Chemical cleaning
Ultrasonic immersion cleaning
Dry ice blasting
Soft plastic media blasting
Laser cleaning
Each type of cleaning process can be used for different applications.
Chemical Cleaning
A chemical cleaning process could be a chemical bath and manual scrub or hooking up the cooling channels to a chemical recirculation circuit to remove fouling and mineral buildup.
Ultrasonic Immersion Cleaning
With Ultrasonic immersion the cavitation bubbles effectively scrub all of the surfaces of the mold.
Dry Ice Blasting
Dry ice blasting is great for cleaning the injection mold while installed in the injection machine.
Soft Plastic Media Blasting
While typical sand blasting media would damage a mold surface, soft plastic media blasting cleans the mold surface without damaging surface texture and polish.
Laser Cleaning
Lasers will burn off mold contaminants and reflect off the clean metal surface.
It’s important to clean the mold just enough to do its job. Over cleaning can damage the mold surface and strip the mold of any protective surface coatings that were applied.
Cooling water is a big issue.
Injection Molds are notorious for cooling channels clogging up due to poor water quality. This results in slower cooling rates and ultimately slower injection mold cycle times. Since time is money in any manufacturing process, looking into ways of reducing cycle time can have a major impact on your bottom line.
A half-second or one-second increase in mold cycle time can result in thousands or hundreds of thousands of dollars in lost productivity.
Surface Coatings & Injection Mold Maintenance
Another option for keeping those water lines flowing is applying the right cooling channel surface coating. In addition to the cooling channels benefiting from surface coatings, injection mold core and cavity components benefit from PVD coatings as well. The right coating will increase mold life and lead to longer preventative maintenance intervals.
Injection mold gas vent performance can be increased with the proper polish and surface coating. Polishing mold vents to SPI A-3 and adding the right surface coating allows the residue that would normally build up and clog vents to flow through the vent and deposit into the vent dump, keeping the venting clear and open longer.
We use our Six Point Injection Mold Program to clean your molds and apply the appropriate surface coatings. Here’s how it works:
Thoroughly clean the mold surfaces.
Clean and flush the cooling channels.
Check the flow rate and complete a leak integrity check.
Coat the core and cavity with PVD A10™ Coating <5 microns thick (will not throw mold out of tolerance).
Coat the cooling channel with proprietary cFlow™ aerospace grade ceramic coating.
Deliver the mold back to your front door for a long and fruitful life pumping out parts.
It’s an end-to-end program that extends the life of your molds.
Ultimately, People want their molds to run more efficiently and longer in between preventative maintenance.
Injection mold repair and maintenance are critical to achieving these goals. After cleaning an injection mold, surface coatings can be applied to the mold core, cavity, and cooling channels to slow down the buildup of residue that can clog mold vents and constrict cooling channels.
Surface coatings make the process of removing the residue and fouling faster when cleaning is needed. These improvements result in lower costs as the mold will need to go into the toolroom for maintenance less often, and when the mold does go in for maintenance, the turnaround will be faster because the surfaces are easier to clean with the proper surface coating.
In order to determine the damage status of the mold and repair measures, processing companies should measure the dimensions of the final molded plastic parts and test the performance of the mold when the mold and injection molding machine are operating normally. Through this information, the damage to the cavity, core, cooling system and parting surface can be found, and the existence status of the mold can be determined.
Mold surface maintenance
What directly affects the surface quality of the product is the surface maintenance of the mold. The focus is on corrosion prevention. Therefore, it is particularly important to choose appropriate, high-quality, and professional anti-rust oil. After completing the production task, the mold should adopt different methods according to the injection molding. Carefully remove the remaining injection molding. When removing the remaining injection molding and other deposits in the mold surfaces, you can use copper wire, copper rods and professional mold cleaning agents, and then air dry.
Handling and Storage Techniques:
Proper handling and storage of plastic injection molds are essential to prevent wear and damage. This includes careful transportation of molds within the facility, using appropriate lifting and moving equipment to avoid drops or impacts. Storage is equally important; molds should be stored in a clean, dry environment, ideally in a way that avoids any unnecessary stress or strain on their components. Regularly cleaning and covering molds when not in use also helps protect them from environmental factors.
Impact of Improper Maintenance:
The consequences of neglecting injection mold repair and maintenance can be far-reaching. Poorly maintained molds often result in low-quality plastic parts, increased rejection rates, and even damage to the injection molding machine itself. This not only affects the production efficiency but also significantly elevates operational costs. Regular malfunctions and downtime for repairs can lead to lost production opportunities and can tarnish a company’s reputation for reliability and quality.
Importance of a Detailed Maintenance Plan:
A comprehensive maintenance plan serves as a roadmap for routine checks and interventions. It should outline specific tasks, frequencies, responsible personnel, and record-keeping procedures. This plan should be a living document, regularly reviewed and updated based on the performance and issues encountered with the molds.
The importance of proper mold cleaning procedures is a topic that is often overlooked in discussion and practice. All too often, mold cleaning is a rushed and not totally effective in removing all residues from the mold surface. In the case of semi-permanent mold releases, poor cleaning prior to application can result in major product failures, poor surface appearance, or lower production from each release preparation.
To prepare a mold for an initial application of mold sealer or release, the mold should be stripped clean of all previously used releases, compounds, and polishes as well as any dust or dirt. By comparison, the goal of cleaning the mold while in process, is generally quicker and more superficial, since the intention here is to keep molding debris from building up and allowing production to run longer before the mold needs to be removed for refinished. Remember that bits of residue from molding are like magnets for more buildup. A quick cleaning while in process can really improve productivity.
It is easier to correctly and completely strip a mold if you know what is on the mold surface. With or without this information, you may find that more than one cleaner or stripper is needed to get the job done. Many people are surprised to learn that some residue, like polish, may be easier to remove with water than solvent. When in doubt about where to begin with cleaning, start by washing the mold with warm water containing two drop of liquid soap / liter. After this, rinse and dry the mold and move on to a quick flashing solvent cleaner.
One indication that a mold is really clean is to employ a simple “tape test”. To do this, you should use a good quality paper masking tape, applying several strips in various areas of the mold, and rubbing over each strip with equal pressure as you apply. Try to use the same tape for your all of your tape tests, as there can be considerable variability in various brands of tape. Once the tape strips are in place, pull them off of the mold surface. A clean mold should yield a feeling of consistent resistance in removal and you should hear some noise as the tape rips free from the mold surface. If the tape in one area releases easier, it indicates that additional cleaning is required. If all of the tape strips release with little resistance, then the entire mold needs more cleaning.
In some cases even the tape test fails to uncover some surface residues, so another good double check is to drop a few beads of water or acetone on what you believe is a clean mold. If this beads up tightly like rain on a new umbrella or rain jacket, rather than immediately making a little pool, you will know that there are still some contaminants on the mold surface-keep cleaning.
Don’t simply assume that because a mold surface looks clean, that it is clean. Many polishes and cleaners may leave a mold looking clean and shiny, but they may have used waxes, oils, or silicone to fill tiny scratches and achieve this “clean look”.
Before testing a new mold release; converting from one release product to a different one; or returning a mold to production after polishing; it is critical to assure that the mold surface is clean. In addition, new molds surfaces should also be cleaned before application of sealer or release products. This includes new metal molds which may contain residues of cutting oils or plating chemicals. A clean mold surface is essential for all sealers and release products, allowing them to wet the mold surface evenly and completely when applied. For semi-permanent mold release products, a clean mold surface provides the site for sealers and releases to cross-link and bond to the mold surface. Without this clean surface, the semi-permanent release will be sacrificed during the first de-molding