Category Archive: Uncategorized

We passed the ISO Audit with Flying Colors!

ISO 9001 Audit
Stern Rubber Company recently completed their annual surveillance audit for their ISO 9001:2008 registration.  To maintain their registration, they are required to go through an annual surveillance audit, and a full recertification audit every three years.  The recertification audit will be performed in June of 2016.
ISO 9001 is an international recognized quality management system that helps organizations ensure that they meet the needs of their customers and stakeholders, while meeting statutory and regulatory requirements related to the product.  It deals with the fundamentals of quality and is based on eight management principles: customer focus, leadership, involvement of people, process approach, system approach to management, continual improvement, factual approach to decision making, and mutually beneficial supplier relationships.
Third party certification is required to confirm that organizations meet the requirements of ISO 9001.  There are over one million organizations that have been independently certified worldwide, which makes it one of the most widely used management systems in the world.
An organization applying for ISO 9001 certification is audited based on an extensive sample of its facilities, processes, and products.  The auditor notes any findings of nonconformities, observations, and opportunities for improvement.  If there are not major findings, the certification agency will issue a certificate.  If nonconformities are found, the company must put together a corrective action that adequately address the issue found, and once the certification body is satisfied that the problem has been resolved, they will issue a certificate.
The ISO 9001 is currently going through a revision, and the new standard will be 9001:2015.  This revision puts more emphasis on risk assessment.  Stern Rubber’s recertification audit in 2016 will be based on this revised standard.
During the latest surveillance audit at Stern Rubber Company in June, the auditor had no findings!   Congratulations to all the employees who worked hard to ensure the company was ready for the audit!

Bonding Rubber To Metal Or Other Substrates

Rubber To Metal Bonding
Bonding rubber to metal or other substrates, is a process that is our backbone at Stern Rubber Company, and is done at both of our facilities in Staples, Minnesota, and Aitkin, Minnesota.  The term rubber to metal bonding is a generic phrase that employs the process of chemically bonding an elastomer to a pre-coated steel surface. Three elements create the bases of the bonding process, the rubber selected, the bonding agent and the substrate of metal.
Choosing a rubber to be bonded to metal is narrowed to how the final part is to be used, that is what kind of environment the rubber to metal part will be subjected to.  Considerations need to be reviewed for UV light, exposure to grease, gasoline, chlorine, heat, cold, chemicals and many more.  Stern Rubber Company can assist with the selection of a suitable rubber.
The metal insert is another key ingredient to the process; first the metal insert needs to be cleaned and degreased, getting the insert completely dry is the next step in the application.  The next step is to apply a primer coat to the insert, followed by another drying application, and finally, bonding agent is applied and finished off by completely drying the final coat.  Once the metal insert has the bonding agent applied to part, it can be over molded with the selected rubber and vulcanized.  At Stern Rubber Company, we use a proprietary metal treatment process to prepare the substrates for the bonding agent.  We apply the bonding agent used at our facility in Staples, by dipping the insert, pneumatically spraying over the part, or by painting the inserts by hand. Using our stringent controls to carefully monitor the thickness of the film of bonding agent being applied to the insert, this insures that our bonding process meets our customers’ demands and we produce quality rubber parts.
Just like science, the vulcanization of the chemical bond occurs simultaneously with the cure of the rubber elastomer, thus the bonding agents are designed to specifically react with the rubber’s process under the right conditions.  Stern Rubber Company achieves maximum bond strength which is obtained under pressure inside the mold cavities. Our processes of compression molding, transfer molding and injection molding all work to create a solid bond between the metal and the rubber part. While there is an application for rubber to metal bonding of inserts into rubber extruded parts, the process is called co-extrusion and used in automotive industry for seals around windows.
Some of the rubber to metal bonded parts that we create at Stern Rubber Company for our customers are gate valves used in the water industry, isolators to reduce vibration, mounting bracket for engines and much more.  Stern Rubber Company can also bond rubber to other substrates which includes other rubbers, plastic, cables, fiberglass, cords of nylon, rayon or Kevlar materials and various metals such as aluminum, steel, iron or aluminum castings.
Give Stern Rubber a call if you need help with a project that needs to have rubber bonded to metal or some other substrate.

Natural Rubber – From a Gooey Sap To A Usable Material

Natural rubber used at Stern Rubber Company is made from a natural source as it is tree sap.  Many consumers think that all rubber is associated with natural rubber, but natural rubber is only one type of rubber which includes different synthetic rubbers like EPDM, Silicone, Polychloroprene, Flourocarbon, Butyl, SBR, and Nitrile.
Natural rubber, which is also referred to as India rubber or caoutchouc, in scientific terms means that it is polymers of the organic compound isoprene, and is classified as an elastomer.   Rubber is harvested from rubber trees, which are a family of trees that belong to the family Euphorbiace; Hevea brasilienisis or Sharinga trees are the most common.  Natural rubber is extracted by method called tapping, by making incisions into the bark and collecting the fluid into vessels attached to the rubber trees.  The liquid is a sticky, milky sap called latex, and requires a couple of steps before it will be sold as natural rubber.
Once the latex is collected from the plantation, is rushed to the processing plant, which prevents the latex from coagulating naturally and rendering the latex useless.  At the processing plant near the plantation, the latex is heated and mixed with acid ammonia which forms rubber like curds; sulfur can be added to create a harder and more stable mixture.  Much like making cheese, the rubber curds float to the surface of the liquid and is skimmed off the top and run through heavy rollers to remove excess water.  The sheets of natural rubber that are formed are cut and stacked ready for shipment to rubber molders like Stern Rubber Company.

In the early 1830’s, natural rubber was used extensively, as “rubber fever” caught on, as everybody wanted things made of the “new” waterproof gum from Brazil, and factories sprung up to meet the demand.  Unfortunately, this faded away as fast as it caught on, as the public become fed up with the messy stuff which froze bone-hard in winter and would become sticky and fall apart in the heat of the  summer.
Charles Goodyear is credited with the invention of the process of vulcanization of natural rubber (and the process that is used today at every rubber molding company) that ended up solving the issues that plagued the early commercial uses of gum rubber, and it gained widespread use soon afterwards.
Located in the jungles of the Amazon rainforest in Brazil, the jungles of Asia, Malaysia, Thailand and Indonesia, the rubber producing plantations create the majority of natural rubber for the world.  During World War 2, with Japan occupying the majority of the jungles in south East Asia, the United States had to find an alternative source for rubber, so research was funded that created synthetic rubber which was used to win the war.
Natural rubber is a very useful rubber and is used extensively at Stern Rubber Company.  Besides from being extremely waterproof; it also has high resilience and stretch, and is often used in pneumatic applications such as tires.  Natural rubber is often mixed with synthetic rubber to optimize the properties of both materials.  While Stern Rubber does not produce them, the application for natural rubber that most people are familiar with, is rubber bands.  Some of the parts that are produced at Stern Rubber include pneumatic plumbing test plugs, gaskets, and suction cups.

QA Gets New “Digs”

Stern Rubber Company’s Quality Assurance Dept. is moving into a newly remodeled space.  The company has added a significant amount of equipment to this department in the last few years, and they had outgrown their room.
Once the building addition was completed in January, the trimming and deflashing departments were moved into the new addition to get them near the end of the process.  This left room to install some additional manufacturing equipment where the deflashing equipment was located, and left the old trimming room available for Quality Assurance to move into.  The space was gutted and remodeled with new windows, insulation, sheetrock, and new climate control equipment.  The space is now finished, and QA is moving in!
In the last two years, Stern Rubber has replaced the rheometer, and has added a Creaform EXAscan Laser scanner, a Makerbot 3-D printer for making measurement fixtures, and a Keyence IM-6120 Vision Measurement System, and added a 3rd person  to the department, so they were bursting at the seams.  The new space leaves room for additional equipment, additional personnel, and even gives them room for storage of initial tooling samples.
This move had to be carefully coordinated, as the equipment all had to be recalibrated as soon as it was moved.
Once QA gets fully moved into their new area, the old QA area is going to be renovated, and is going to become the new Technical office.  The Technical Dept. is temporarily located in the old front offices, as their old office was torn out to make room for an injection press that was added a few weeks ago.  As soon as they move out of their temporary location, that space will be renovated as well.  (Stay tuned for what that will be used for!)
It is an exciting time for Stern Rubber as they have added space for manufacturing, improved the material flow, added new offices and main entrance, and now remodeling some of the old spaces for much needed improvements!

Stern Rubber Company Adds NorMec Splicing Press

Stern Rubber Company adds NorMec Splicing Press
Stern Rubber Company is adding to its capabilities by purchasing a Normec Automatic Splicing Press.  This will be used to make gaskets by joining the ends of an extrusion, to form a continuous gasket or seal.  This press and process will replace the manual process of gluing extrusions.
NorMec has been building splicing presses for more than 20 years, and the latest one is the most advanced splicing press in the market.  Normec is known to have world-class hot and infrared splicing solutions.
Normec is such an industry leader, that hot splicing is often referred to as the “Normec method”.   Hot-splicing of extruded rubber products yields superior quality and higher throughput than alternative splicing techniques. Having pioneered hot-splicing, Normec continues to be the global leader in providing reliable, flexible, and scalable hot-splicing solutions. They have provided solutions to splice EPDM, NBR, SBR silicone, PVC, TPR and other materials.
This splicing capability adds to and complements the current extrusion capabilities at Stern Rubber.  Stern currently has two 3 1/2″ extrusion lines.  The first utilizes a microwave/ hot air cure oven and 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 second utilizes 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,  cooling bath, rotary cutter, and an automatic winder.
The extrusion and splicing capabilities complement Stern Rubber’s compression, transfer, and injection molding expertise.
Please click below for a link to Normec’s website to read more about this process and equipment.
Please click here for a video of this press in action.
Please contact Stern Rubber’s Customer Service Dept. to get a quote on your extrusion or molding project!

Added Capacity With Another Desma Injection Press

Stern Rubber Company is adding to its capacity by adding an additional Desma injection molding press.  The new press is an Alpha 250, which has 250 metric tons of clamp pressure.  This press will be outfitted with a 2000 ccm (cubic centimeter) injection unit, and is customized to allow it to run a rotating core bar, to further reduce cycle time, and reduce final part cost.
This press is the fourth of this size and style from Desma that Stern Rubber Company has installed in its Staples, MN facility.  Stern Rubber Company’s injection capabilities also include a 560 metric ton Desma Benchmark press, and an 800 metric ton Rutil in its Staples, MN location, as well as three 560 metric ton Desma presses in its Aitkin, MN facility.
Desma was founded in Germany in 1946 under the name Deutsche Schuhmaschinen and Company, U. E. Ludwig KG, which was under the brand name DESCO and created machinery for shoe production. It 1953, the brand changed its name to DESMA, still producing shoe soling machinery. Today DESMA has over 4,500 injection presses operating, and over 500 employees in location around the world, DESMA is one of the finest injection presses to mold rubber.
Stern Rubber’s capabilities also include 29 compression/transfer rubber molding presses with platen sizes ranging from 10″x10″ up to 24″x60″ and 42″x42″, 2 rubber extrusion lines, and cryogenic deflashing equipment.
While Stern Rubber molds rubber parts using compression, transfer, and injection, injection is usually the most economical, but there are longer set up times, so this process is usually used for higher volume projects.  Besides cost, the other advantage is tolerances.  Because the mold is clamped shut before the material is injected, this process is normally capable of holding tighter tolerances than transfer or compression.
The injection molding press takes the rubber into the press as a strip of thermoset elastomer rubber (TSE), and is fed into the barrel of the injection press, where the raw rubber is warmed in a screw to just below the operating temperature of the mold. The warmed rubber is then injected through the feed channels in the steel tool, passing into the cavities of the mold, where it is formed into the shape of the desired parts over a metal mandrel, or over a metal insert inside the cavity, to bond the rubber to the metal, or into a solid part. Vulcanization occurs when the pressure, temperature and desired time creates a chemical bond and crosslinks the rubber. Rubber injection is a far faster process than that of compression or transfer molding, since the rubber is preheated before it enters the cavities of the mold, reducing the cure during vulcanization.
Stern Rubber Company’s Project Coordinators and Technical Group will be happy to work with you to recommend the most economical way to produce your part.

Meet Stern Employee Keri Kuklok

Meet Our Employee Keri Kuklok
Keri was born in Long Prairie, Minnesota and grew up in Motley, Minnesota.  Both Motley and Long Prairie are neighboring towns to Staples, where Stern Rubber Company is located. Keri now lives only five miles from where she grew up, south of Motley, near Lincoln, Minnesota.  Keri studied architectural construction technology and has an Associate of Applied Science (AAS) from St. Cloud Technical College.
Keri is one of our newest team members at Stern Rubber Company, and she is our Office Assistant and Receptionist.  As the receptionist, she is the smiling face that first meets all of our visitors, and the voice that usually answers the phone.
Keri assists our accounting, customer service, and human resources department, and has taken on the responsibility of our employee training.  Keri wears many additional hats here as well, with her fire training she is part of Stern Rubber’s Safety Committee, and she has given training on fire extinguishers and State of Minnesota’s Right-To-Know program (OSHA).   She started with Stern Rubber Company in December of 2014. Prior to starting with us, Keri did construction and drafting for her Dad’s business. She also did design work and drafting for architects in our area.
Since 2002, Keri has been an EMT (emergency medical technician) and First Responder, and joined the Scandia Valley Fire Department in 2009.  Her husband, Ryan, is the new Fire Chief in Scandia Valley Township, and her Dad is the retired Fire Chief, so I guess you could say fire fighting is in her blood!  She is the committee chairperson for Scandia Valley Summer fest.  This festival is held Friday through Sunday, July 31st through August 2nd 2015.  There will be a street dance with a live band, Fireman’s turkey BBQ, fireworks and much more.
She was married to her husband, Ryan in 2001 in Cozumel, Mexico.  They have two children, Natalee, who is five years old, and Evan, who is three years old.  As a family, they love to enjoy the outdoors and their hobby farm.  On their hobby farm they have rabbits, chickens, geese, pot-belly pigs, dogs, cats and four amazing, fainting goats which are her other “kids”.  The whole family enjoys taking care of the hobby farm.  As you can see, they are one busy family!
Her husband’s favorite hobbies is trapping animals for their fur and making maple syrup. Keri just shot her first deer last fall with a bow and arrow, and now she is excited about trying fishing this spring with her bow.  Her family enjoys being together; they go horseback riding, camping, hunting, fishing, doing crafts, and just playing with their kids, both the human ones, and the fainting ones!

American Valve & Hydrant Supplier Of The Year

In May, Stern Rubber Company sent a team to visit our customer, American Valve and Hydrant in Beaumont, Texas; to accept the Supplier of the Year Award in the Molded Rubber Category for excellence in delivery and quality. American Valve and Hydrant gives this award to one supplier in each of their purchasing categories. Stern won with a score of 100% in quality and 100% on-time delivery.
Since 2003, Stern has been winning awards with American Valve and Hydrant, we also won awards for Supplier of the Year in 2003, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 and 2014.  That is ten years in a row and eleven total of winning the supplier of the year molded rubber category.
Since 1969, Stern Rubber Company has been a leader in the molded rubber industry; This custom rubber molding company was formed by Terrel Stern and his father Donovan Stern in Savage, Minnesota, and moved to Staples, Minnesota in 1973. In our company history of molding rubber products, Stern Rubber Company is 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 market.
Stern Rubber has three locations, one facility dedicated to molding products for American Valve and Hydrant and Waterous located in Aitkin, Minnesota. We have a bonding process and three rubber injection molding presses that produce rubber to metal bonded gate valves.  We also produce rubber products at our main facility in Staples, which also includes compression molded valves and rubber gaskets.
Accepting the award from our buyers at American Valve and Hydrant was Sandy Mumm, Vice President of Operations, Mickey Farber, Customers Service Representative, Barry Hirschey, Sales Engineer and Rich Swearengin, Business Development and Marketing Manager.
Producing quality products and delivering them on-time is what Stern Rubber Company has been known for in the rubber industry. We would like to thank everyone at American Valve and Hydrant, our employees and our suppliers for this Supplier of the Year award in 2014.

Minnesota Makes Big Waves When It Comes To The Fishing Opener

Our team members at Stern Rubber Company are planning on taking advantage of the Minnesota Walleye fishing opener, happening May 9, 2015. Even our governor, Mark Dayton, is taking advantage of this huge event in Minnesota.  Last year, Mark Dayton fished on Gull Lake, which is about thirty minutes to the east of our location in Staples.  This year, the governor will be fishing on Lake Vermillion, which is about an hour north of Duluth, Minnesota.  This is very big business for northern Minnesota, since we have the best walleye fishing in crystal clear lakes, formed by glaciers, in our last ice age.
The walleye is Minnesota’s most desired fish, known for its pearlescent eye, which is caused by a reflective layer of pigment; which helps the walleye to see and feed at night, or in murky water.  The walleye is excellent to eat; it has thick, white fillets that are served in many restaurants in our area and across the state.  Minnesotans will keep about 3.5 million walleye this year, which will total almost four million pounds of fish. The ideal size to render enough meat is a walleye about one pound and measures about fourteen inches in length.  Native to Minnesota, the walleye flourishes in lakes that are large, shallow, with gravel shoals, which are exactly the lakes we have in central Minnesota, and why most anglers come to our area during walleye fishing opener.
Gearing up for the walleye opener is also huge business for area retailers, including one of the largest retailers, who started in 1922 in Brainerd, MN, Mills Fleet Farm.  Other retailers like Walmart, Gander Mountain and many local resorts and bait shops, stock up on fishing poles, lures and boating supplies to get anglers ready for walleye opening day.  Located also in our area are many boat manufacturers.  One of our customers is Lund boats, which is located just west of Staples, in New York Mills, MN. Another customer is Lift Tech Marine who manufactures boat lift drive motors in Brainerd, MN; we produce a rubber to metal bonded drive wheel.
Many hotels, campgrounds, and resorts are located around Stern Rubber Company.  If you don’t have a cabin to stay at, you will need a place to recover from your hours on the water, waiting for the walleye to bite.  Some of the largest and most well-known resorts are Cragun’s Resort, Maddens Resort and Grandview Lodge.  The best lakes in our area to fish are Gull Lake, North Long Lake, Lake Mille lacs, Leech Lake, Whitefish Chain of lakes, Fish Trap Lake, Lake Alexander and Lake Shamineau.  River fishing is also an excellent way to catch walleye’s; our local rivers include the Crow Wing River and the Mississippi River.
The record for the largest walleye caught in Minnesota was seventeen pounds, eight ounces, it was 35 ¾ inches long and had a girth of 21 ¼ inches. It was caught in the Seagull River at Saganaga Lake in Cook County, (which is in the Boundary Water Canoe Area) in northern Minnesota on May 13, 1979, which was the walleye fishing opener for that year.
Visit for more information about the Brainerd Lakes area and fishing for Minnesota Walleye opener; at this site you will find additional information about resorts, lodging, shopping, weekly fishing reports, golf, biking and much more.

Quality Assurance Manager Job Opening

Stern Rubber Company in Staples, Minnesota is seeking a Quality Assurance Manager for our rubber manufacturing company.  This QA manager will be responsible for managing the Quality Department of an ISO 9001 Certified Company, managing our quality team, and providing Quality Assurance support for our three locations, to our customers and suppliers.


Develop, implement and manage Quality systems
Maintain ISO 9001 requirements
Provide reports regarding Quality performance
Audit corrective actions
Participate in the qualification of new products and processes
Train and support the Quality staff
Responsible for Quality budgets
Manage all internal and Customer audits
Communicate Customer and vendor needs to the plant
Maintain Quality equipment (gages, computers, software, etc…)
Travel, 25% (domestic and international) passport is a must
Positive attitude


5 years experience as a Quality Manager
3 years experience as a Quality Coordinator, Quality Engineer, or related position
ISO 9001 Experience (Required)
Ability to read, analyze and interpret blue prints, technical procedures and criteria or specification information
Knowledge of good manufacturing practices (cGMP)
Excellent communication skills, writing and verbal
Manufacturing experience


4 year degree in engineering preferred, but experience will be considered in lieu of a degree
3-5 years in a supervisor role
Previous quality experience

We are seeking a motivated individual who is interested in an exciting position utilizing state of the art technology to provide the highest possible level of quality for our customers.  They must be able to communicate with a diverse group of people and education levels, and practice, reinforce, and promote sound quality and customer relations for both internal and external customers.
Stern Rubber Company has been the industry leader in rubber manufacturing since 1969, specializing in custom rubber molding and rubber extrusion. Located in Staples Minnesota, we are a fast-paced growing company looking for talented individuals to join our team.
To be considered for this position, please send your resumes to the attention of Amanda Jans.
Mailing Address: Stern Rubber Company, PO Box 69, Staples, MN 56479
Fax: 218-894-3124
EOE M/F/Vet/Disability