Günther Hot runners to the fore in production of writing instruments

Author / Editor: Barbara Schulz / Barbara Schulz

Germany – For 70 years, Wernigerode-based company Schneider has been producing high-quality writing instruments. The company’s continued success today, which includes the production of 80 million ink cartridge cases each year, involves systems from Günther Hot-Runner Technology.

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For 70 years, Schneider has been producing high-quality writing instruments. Today, the company produces 80 million ink cartridge cases each year.
For 70 years, Schneider has been producing high-quality writing instruments. Today, the company produces 80 million ink cartridge cases each year.
(Source: Günther/Schneider)

Schneider can look back on a 70-year history to its founding as Heiko Schreib- und Zeichengeräte in 1946. Following German unification the company was taken over by the firm of Schneider Schreibgeräte in Tennenbronn in 1991 and founded a new company with 56 employees under the name of Schneider GmbH Co. Productions- and Vertriebs KG.

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Today Schneider has a staff of 135 employees and a production floor space of 8,700 m², producing writing products that are sent all over the world. Its injection moulding department comprises 28 injection moulding machines and there are other departments for assembly, printing and design as well as a tool shop. The company places a high degree of value on providing its own training for its future employees. As a rule, all apprentices are given employment in the company at the end of their apprenticeship.

Hot runner systems were first used in the injection moulds in the year 1994 with the goal of increasing production capacity. The first hot-runner system for indirect injection in a 72-cavity production mould for ink cartridge cases made it possible to triple production capacity. Today over 80 million ink cartridge cases are produced each year, the cartridge cases also filled, sealed with glass balls and then packed at Schneider.

Working with the firm of Günther Hot Runner Technology from Frankenberg (Eder) in North Hesse, Germany, Schneider was able to reduce material consumption by eliminating thick-walled gating systems which also significantly reduced the cycle time because of the shorter cooling time.

In a next step the moulds were equipped with an even greater number of cavities and with more hot-runner technology. Open hot runner nozzles with a two-part shaft and naturally balanced manifolds are used. The gating is done with a subrunner, which ensures the cores’ position stability. The two-part nozzle shaft made of titanium alloy and tool steel allows, in a confined installation space in combination with the integrated air gap in the hot runner nozzle, a very good thermal separation between the hot runner and the temperature-controlled mould.

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Reduced cycle times, optimised energy input

Using Günther hot runner technology Blue Flow nozzles meant that the cycle time could be reduced by a further 4 seconds. These nozzles have special thick-film heating elements with 55% of the energy in the area of the tip. This reduces the required temperature input into the melt.

Environment-friendly production with savings in energy and resources is a strategic goal for Schneider. This has been proven by repeated EMAS certification since 1998. The use of hot-runner systems is an important element in reducing the amount of plastics required in the process. In addition, the Blue Flow nozzles in combination with the two-part shaft need significantly less energy and help meet the requirements of EMAS certification.

The production of ink cartridges is just one part of the product manufacture at Schneider; other business units comprise the production of high-quality pens and text highlighters. Multi-component injection moulding is increasingly used in the production of these parts. In the multi-component injection moulding various materials are combined together in the injection mould.

As a rule, a lot of new articles have a softer, ergonomic gripping area made of an elastomer such as TPE or TPU and a harder basic body made of PE, PP or ABS plastics. Up to 16 different colour combinations are produced for individual writing instrument series. The range of colours makes it necessary for the hot runner system to have good colour changing properties to allow a very rapid change from one colour to another during production. Likewise, as the colour batches are temperature-sensitive during processing they require a homogeneous development of temperature over the entire melt channel in the hot runner system without temperature peaks.

The company’s marketing and sales departments place an increasing focus on surfaces, contours and the visibility of the products. This requires more use of valve-gate hot-runner systems. For the new Schneider “One“ series of ink pens both Blue Flow nozzle types - 6NHF100LA-1.0S and 5NHF100VA-0.8S - are used in the 2-C injection moulding process. To ensure that the needles open and close the injection points precisely and evenly, the pneumatic version of a lifting plate is used as a drive. These lifting plates are moved by the corresponding quantity of cylinders and equipped with special guide elements to allow operation with process reliability.

To guide the coated needles in the valve-gate nozzles, needle guides made of powder metallurgical steel are used close to the gate. This ensures a long service life. The valve-gate hot-runner system was delivered as a hot half completely assembled and wired by Günther.