Category Archive: Uncategorized
Rodney is our lead rubber molder at our Aitkin, Minnesota plant or plant number 3. His duties include getting the presses started in the morning, by making sure all the equipment, tools, EPDM rubber and castings are set up at work stations. Plant number three has three injection presses, a bonding room and warehouse; the injection presses inject preheated rubber into the cavities and bond rubber to metal castings. American Valve & Hydrant and Waterous Company are the two customers for the gates valves that we manufacture for the water industry. During Rodney’s shift he runs an injection press, loads and unloads trucks with casting and completed gate valves, including completing the paper work for the loads shipping each day, and he gives breaks to the other operators at our third plant. If you call plant number three, Rodney is the person that usually answers the phone.
Rodney started with Stern Rubber Company in 1998 and was one of the very first employees hired for the Aitkin plant. Prior to working for Stern, Rodney worked in Chaska, Minnesota at Pies Inc., which was a foodservice company specializing in creating over 350 different frozen pies for school, restaurants and institutions. Rodney loaded trucks and filled orders all while working in sub-zero temperatures in the company’s freezer. Rodney grew up in the western suburbs of the Minneapolis, in Minnetonka; he was born and raised in Victoria, Minnesota, which is just south and west of Minnetonka.
Rodney will have been married for twenty-five years to his wife this coming June. He has one daughter; named Amanda who lives in Nebraska with her boyfriend and his son, Tony, who is now fourteen and in eighth grade attending Aitkin High School, and is an athlete in track and field.
Rodney earns extra cash by mowing lawns for people on the weekends, but he says it more of a hobby than a job. He does the usually things that people here in northern Minnesota do, like taking long walks in the woods, fishing on crystal clear lakes, taking bike rides with his family and hunting for birds and deer. He also does woodworking in his free time, but when you have so many activities in the north land, your free time is a premium.
After our new addition was completed, where we added about 12,000 square feet to the main building (plant number one), the first department to take advantage of the extra room was our cryogenic deflashing and rubber trimming departments. We created a space on the first floor that houses a room for the trimming and inspection department. We moved our two cryogenic deflashing units to the north wall and move the 6,000 gallon liquid nitrogen tank to the outside of the south wall.
Since 1969, Stern Rubber Company has been molding custom rubber products and rubber extrusions at three locations in Minnesota. When we mold parts for production, we precisely weigh out our raw rubber before we mold our products on the compression and transfer molds; we make sure that only a small amount of flash is created around the rubber parts so that we guarantee that we don’t have under filled parts, which would render our parts unacceptable by our customers. In our rubber injection presses this is governed by computer, so that they too only leave a small amount of rubber flash on each part. Rubber flash is the material the oozes between the seams of the top and bottom portion of the molds and is usually about 1 micron thick. Removing this flash from the parts is necessary and we employ two applications for its removal: freezing the part in our cryogenic deflashing units or hand trimming of the part.
Cryogenic deflashing is taking rubber parts and putting them in a basket or a moving conveyor inside the cryogenic unit. Shutting or closing the unit’s door and injecting liquid nitrogen to freeze the flash only, the rubber parts don’t freeze and we use a large amount of small plastic beads driven by air to pulverize the rubber flash from the rubber parts. The rubber flash become brittle at an approx. temperature of -40⁰F, which allows the rubber to breakaway freely from the rubber parts, rendering 99% of the flash is removed. The liquid nitrogen can actually get as low as -275⁰F, but we would never want to get rubber parts that cold, as it would simply break them into tiny pieces during the tumbling process. In many of our applications ninety-nine percent is acceptable since it is not seen as a cosmetic application.
In our hand trimming department, removing 100% of the flash is necessary and each part is trimmed by a skilled trimmer who handles each part using a lighted magnifying lens or light to insure the parts are free of rubber flash. This process adds cost to the part price since this is a labor intensive and time consuming activity, but is necessary in order to create a high quality rubber part. Some of our parts are tiny in size and requires delicate and very precise trimming, while other parts are larger, but still have similar needs in trimming, it is just easier too clear away the rubber flash.
Once the molded rubber products are cleaned of the rubber flash, they are cleared to be shipped to our customers. This is why we moved our trimming and deflashing department into our new addition, closer to the shipping department as it improves our flow of product. With the increased space, we also added more warehouse room.
Stern Rubber Company has three locations located in Minnesota; two plants are in Staples and the third is located in Aitkin. The Aitkin plant, or plant number three, is dedicated to producing rubber to metal bonded gate valves for two of our customers: American Valve and Hydrant in Beaumont, Texas, and Waterous Company in South St. Paul, Minnesota; these valves are used in the water industry meeting NSF 61 requirements.
The process for manufacturing these products is by bonding rubber to cast iron valves by injection molding; we clean and prep the cast valves, apply bonding agent material to the cast valves and encapsulate the casting with EPDM rubber. EPDM rubber is an approved rubber used in the water industry since it has good resistance to ozone, oxygen, and both inorganic and organic chemicals. With its temperature range running between -70⁰F and up to +300⁰F, it finds itself resistant to seawater and fresh water. EPDM is not reactive to chlorinated water, which makes this synthetic rubber an excellent application for the water industry.
The injection molding press at Stern Rubber Company plant number three takes the EPDM rubber into the press by strip as a thermal set elastomer (TSE), into the barrel where there is a screw that warms the rubber to temperature which is still below the operating temperature of the mold. The EPDM rubber is then injected through channels in the tool, passing into the cavities of the mold and encapsulating the valve castings. Vulcanization occurs when temperature, pressure and time creates a crosslinking of the chemical bonds in the rubber. Rubber injection molding is a faster process compared to compression or transfer molding, since the rubber is preheated before it is injected into the mold’s cavities, which reduces the required cure time. In addition to preheating the rubber, we also preheat the castings before they placed into the mold, which also reduces the time to vulcanize the rubber.
A metal mandrel is used to position the casting in the correct position inside the mold and is removed by a hydraulic press after the injection press completes vulcanization. The next step in the process is the parts are inspected, excess rubber flash is removed and the rubber sprews (feeds) are removed. Our experienced operators apply a black epoxy resin to the area of the valves which had stand-off pins, before adding plastic ears which allow the gate valve to slide easily inside the valve body. Once through our quality inspections the gate valve and packed on a pallet and are ready to ship to Beaumont or South St. Paul.
We have been Supplier of the Year for the past eleven years creating high quality gate valves, gaskets and rubber products for American Valve and Hydrant with deliveries that are always on-time. In 2014, Stern Rubber had 100% on time delivery and 100% quality.
Neoprene or polychloroprene is a synthetic rubber that is flexible at different temperatures, has good oil-resistance and has substantial chemical stability. Stern Rubber Company compounds our polychloroprene in house and does dense rubber molding and rubber extrusion. Neoprene offers good resistance to gasoline, oil, acids and alkalis. Its characteristics make it an excellent application for use in outdoor applications, since it has resistance to UV light, oxidation and ozone. Stern Rubber Company compounds neoprene in a dense rubber form that would be an excellent product that has properties that fall between EPDM and Nitrile. It has a temperature range between -60⁰F to 250⁰F, with a wide variety of applications depending on durometer. Some chemicals can degrade neoprene such as acetone, hydrochloric acid, chlorine and even human urine, which is why you don’t pee in your wetsuit.
DuPont scientists invented neoprene in 1930, but the rights to the patent came from Father Julius Nieuwland, who was a chemistry professor at the University of Notre Dame and was studying acetylene. Nieuwland studied the effects of acetylene could be polymerized to create a jelly like substance called divinylacetylene, which when hardens, forms an elastic compound that was similar to rubber.
The first commercial work done on this new synthetic rubber was done by DuPont’s Wallace Carothers after DuPont purchased the patent rights from the university and also including collaboration from Father Nieuwland. Later DuPont spun off a product of monovinylacetylene and they created chloroprene.
In 1931, DuPont marketed this new compound as a trademarked name DuPrene and started selling this synthetic rubber material to manufacturers of finished end products. In 1937, DuPont changed the name of DuPrene to Neoprene and DuPont is the only producer of the Neoprene brand, polychloroprene in North America.
To create sponge rubber, Stern Rubber uses a blowing agent in our dense rubber formula, so that we can create an open or closed cell foam sponge rubber; using a nitrogen blow agent gives you closed cell and a carbon dioxide agents give you open cell. While in the open-cell, neoprene is more breathable, applications for open cell neoprene include cushioning, sound damping, shock absorption and vibration control. Die cut gaskets are easily cut in neoprene sheet. A closed-cell foam neoprene is less compressible and has good waterproof tendencies.
At Stern Rubber Company, some of the products that we use neoprene or polychloroprene rubber for include motor mounts, CV boots, engine bellows, tie rod boots, grommets, seals and gaskets. Neoprene works well with compression, transfer, injection and rubber to metal bonding and also hoses that can be extruded. Since neoprene works well with electrical application, we mold electrical jackets and onto cables. Although we do not produce wetsuits at our plant, it is the number one use for neoprene.
Stern Rubber Company is adding to its extrusion capabilities by adding a 3 1/2″ NRM vacuum extruder.
After being a custom rubber molder for over 40 years, Stern Rubber Company added extrusion capabilities in 2010, when they partnered with a customer to add a 3 1/2″ extrusion line with microwave/hot air cure to the Plant 2 location in Staples, MN. At the end of 2010, a 3 1/2″ extrusion line with salt bath cure was added to complement the microwave/hot air line.
The microwave/hot air line includes a 3 tier microwave oven, 3 pullers, a cooling bath, and a guillotine cutter, which requires the line to stop to make the cut. The salt bath rubber extruder includes a 40′ salt bath, a two dimensional laser that monitors the size of the part, and modifies the speeds of the puller to keep the part in specified size, a hot water rinse tank, a rotary cutter, and an automatic winder.
Stern Rubber Company has found that the current extruder on the salt line has some limitations in regards to what material it runs well. Some of the current projects include EPDM, neoprene, NBR, butyl, SBR and CPE, including sponge rubber. Some of the materials that have proven to be difficult include natural rubber, and any material that is softer than 50 durometer. Because of these limitations, the extruder will be replaced with one that has a larger L/D ratio (Length/Diameter), and has vacuum capabilities. The vacuum capabilities require the extruder to have a special vacuum screw, and has a chamber located near the center of the extruder that allows the vacuum to pull trapped air out of the material.
Being added at the same time as the new extruder to the salt bath line is an additional cooling and rinse tank. The additional cooling capacity will allow the rotary cutter to hold tighter tolerances on cut length, by allowing the parts to be cooled further, so there is not further shrink, after they are cut.
Give Stern Rubber Company a chance to quote your extrusion projects!
John was born and lived in Freeport, Illinois, until the age of five, then moved to Minnesota until the age of twelve. He moved with his family to Montana and moved back to Minnesota at the age of fifteen. That was his last move and still resides here in the state of Minnesota. After high school, he attended three plus years in technical college, studying tool making.
John is our tool maker at Stern Rubber Company, even though almost all of our rubber molds are made by outside tool makers, with three that are located in Staples. John has the skills to create some of our tools, sample tools and maintain our tooling, so that they work to maximum performance. Stern Rubber Company requires in house maintenance of our compression, transfer, and rubber injection tools and rubber extrusion dies. Rubber molding tools and rubber extrusion dies are the life blood of Stern Rubber Company, since our tools are heated to 380⁰Degrees Fahrenheit, with the rubber being pressed into the cavities, overtime these tools show signs of wear and John is tasked with maintaining them.
Before starting with Stern Rubber Company in 2012, he worked twenty-three years as a tool maker for McKechnie Tooling across the street from Stern Rubber Company in Staples. One position he is very proud of is 20-20 Theatrical, installing rigging and electrical wiring for seven years into theaters around the country.
John is married to his wife Anne and they have been married for thirty-four years. Anne was born and raised in Helsinki, Finland and works in Staples at the United Methodist Church. They have three children, the eldest son Michael is married and he too lives in Staples and has two daughters. The middle daughter Laura is getting married in June and live in Los Angeles, CA and she is a fashion designer. Their youngest son Aleksis is getting married in July and lives in Minneapolis, MN, studying to be a psychologist.
John enjoys to riding his motorcycle and rebuilding motorcycles. He works on his own, but enjoys helping out his friends and other bikers in need. John belongs to the Free Masons, is a member of Zuhrah Shrine Temple and Birak Shine Club. He also rides go carts in local parade as a member of the Kar Kor.
3D printing or Additive Manufacturing (AM) is a technology that creates parts from a wide variety of materials in which the parts are formed layer by layer by an additive process, unlike the original more traditional methods of creating parts by a molding or casting process. The types of material that work best for 3D printing are plastics, metals, paper, ceramics, bio materials and even food. Although there are many different materials for 3D printers, Stern Rubber Company uses an ABS plastic composite material on their Makerbot 3D printer, which prints layer by layer at a micro layer at a time. Stern Rubber typically uses our Makerbot to create fixtures to hold our rubber parts and extrusions.
3D printing first started in the late 1980’s. The earlier process was called Rapid Prototyping technologies (RP). The first rapid prototyping machine was invented in 1980 in Dr. Kodoma, a patent lawyer in Japan. He did not complete the patent application within the one-year deadline, so he wasn’t awarded the first patent. The first patent was issued in 1986 to Charles Hull, for a sterolithography apparatus machine that he had been working on since 1983. Hull later went on to be a cofounder of 3D Systems Corporation, which grew into a large corporation.
Many companies created rapid prototyping machines through the nineties and most were clearly for high end users such as vehicles, automotive, and aerospace companies, since they were geared toward high value, complex engineering and detailed parts. These printers were large and expensive – but there were some manufacturers that were creating smaller desktop versions that were less expensive. After 2007, prices fell drastically. Since then 3D printers have become more affordable for every industry.
As a rubber manufacturer, soft materials and thin wall sections can make it difficult to measure parts using contact equipment, like a CMM. It can also be difficult to get a part in the correct configuration for scanning. To aid in inspection, we would build steel fixtures, which was taking up CNC time and adding cost. Our solution was to create 3D inspection fixtures for CMM inspection and laser scanning. The reduced time and costs for fixtures since adding Makerbot to our quality assurance department has allowed for a quick return on our investment and reduced costs for our customers. With advances in the material that can be printed, we hope to soon be able to use our Makerbot to print flexible proto-type parts for our Customers.
This type of synthetic rubber, ethylene propylene diene monomer, or simply referred to as EPDM rubber, has uses in many different applications. This is an M-Class rubber where the M refers to its classification in ASTM standard D-1418. Ethylene is obtained from petroleum and natural gas and is a colorless, flammable, gaseous, alkene with a sweet odor. Propylene, like Ethylene, is a flammable gas that has a slight odor of petroleum and is a colorless gas, which is obtained by thermal cracking of ethylene. Diene is a hydrocarbon that contains two double bonds of carbons. Stern Rubber Company compounds and mills batches of EPDM rubber for our compression molding, transfer molding, rubber injection, rubber to metal bonding and rubber extrusion.
The origin of EPDM starts with its patent in 1967 by Everett T. McDonel, Brecksville, and Parviz Hamed, in Akron, Ohio, under contract for B.F. Goodrich. EPDM rubber has a good resistance against oxygen, ozone and inorganic and organic chemicals; it also lacks resistance to substances like grease, solvents and mineral oils. EPDM is outstanding in temperature resistance and it exhibits low temperature flexibility; EPDM rubber has a wide range of temperature range from -70⁰F to +300⁰F. What make EPDM an excellent rubber, besides from its good temperature range, is its resistance to water and seawater. In fact, EPDM is not reactive to chlorinated water, which makes it an excellent application for use in the water industry. Our largest customers at Stern Rubber Company, American Valve and Hydrant and Waterous, use gate valves manufactured of EPDM rubber.
Also, EPDM has a wide variety of application in the rubber molding industry and molded or extruded at Stern Rubber Company. EPDM also has resistance to chemicals, and solvents, rendering this rubber for uses in seals, o rings and gaskets. EPDM lends itself to working well with compression, transfer and injection molding processes, as well as the extrusion process for products like rubber hoses, electrical cables, tubing and seals. In addition, other products that work well with EPDM are washers, die cut rubber gaskets, isolators, belts, intake hoses, weather stripping, water pumps and valves. Roofing membranes are usually made of EPDM, as well as rubber sheeting for water collection and pond liners, since it simply does not contaminate the water that the rubber comes in contact with. One of the most common uses of EDPM rubber is in the automotive and vehicle markets, to reduce friction and noise this rubber is used in window seals, door seals, trunk seals and in hood seals.
Today is our grand opening of our new building addition at Stern Rubber Company in Staples, Minnesota. Since 1969, Stern Rubber Company has been the only manufacturer of custom rubber products offering creative solutions and strategic partnerships to innovative companies in North America, who want to lead their industries in a fiercely competitive global market. Since moving to Staples in 1973, we have made a couple of additions to the 900 Prairie Ave Northwest main building and have added the extruded rubber building next door to the main location in Staples. Also we have added the Aitkin plant where we have rubber injection machines that produce gate valves for Waterous Company and American Valve & Hydrant. Our new addition added new offices so that all the staff will be under one roof, added a new area for the rubber deflashing and rubber trimming departments and added warehouse space for off-shore sourcing.
A ribbon cutting ceremony took place today led by our owner and Chairman, Terrel Stern, our CEO Bonnie Gastecki, our President, Bob Jackson and our Vice President of Operations, Sandy Mumm. The local newspaper “Staples World” was on hand to write a story about our new grand opening. In order to not lose valuable working days during the move, we worked nights and weekends to move everyone into their offices. We added new computer network switches and updated the network to better serve our customers. Stern Rubber Company has two floors of offices, with conference rooms on each floor, customer service, purchasing and administration is on the first floor and management and accounting are on the second floor; We have plenty of room to expand offices in the future. After moving our liquid nitrogen tank, we moved our cryogenic deflashing machines to their new location on the south end of the new addition. We also expanded the size of the trimming department which is now also located in the new building addition. We will move our quality assurance lab to the room that trimming once occupied and engineering/estimating will move the space currently occupied by QA.
The general contractor of our building is Hammers Construction who is based in Perham, Minnesota. Stern Rubber Company and Hammers Construction used local businesses to do the construction of our new addition, including Jordahl’s for the concrete, Giza Plumbing and Heating, Derek Holst Construction for the office framing and finish work, Minnesota Valley Irrigation for the electrical, and Brainerd Glass. We will finish our parking area around the new addition when the snow melts and the ground thaws, in addition we will also do some much needed landscaping around the building as well.
Stern Rubber Company is known for rubber molding, rubber to metal bonding, extruded rubber, compression molding, transfer molding, rubber injection molding and rubber compounding and milling its own raw rubber. Our customers know us for our on time delivers, our quality and excellent customer service. With the increased space added by the new addition we will only perform better to meet all our customer’s needs. the new addition we will only perform better to meet all our customer’s needs.
Page 11 of 13« First«...910111213»
