Generation of noise by injection moulding machines during operation is unavoidable. People engaged in injection moulding production are exposed to machine noise for longer periods. Individual noise perception can vary significantly and everyone reacts to persistent noise exposure in a different way. A sound pressure level of as much as 65 dB (A) can potentially cause concentration disorder and negative effects on cardiovascular system. As a result, to avoid negative effects on employee health, noise development in manufacture should be kept at as low a level as possible. A low noise level of less than 60 dB (A) makes working places more attractive and improves employee performance – they make fewer mistakes and work more precisely. Subsequently, the quality of end products increases.
Noise spreads in the air in form of sound waves. Sound intensity is indicated as sound pressure level in decibel (dB). The rule of thumb is that an increase in sound pressure level by 6 to 10 dB (A) is perceived as double sound intensity. Sound pressure level of injection moulding machines is determined according to DIN EN 201:2009 Appendix K to obtain comparable measured values.
Noise emission of hydraulic injection moulding machines can reach more than 70 dB (A). At the same time, all-electric machines generate much lower noise levels during operation. For example, sound pressure level of IntElect series from Sumitomo (SHI) Demag Plastics Machinery GmbH is only 59 dB (A). However, hydraulic injection moulding machines can also ensure a relatively quiet production environment, provided that the machine manufacturer pursues the goal to keep noise level as low as possible already in the development phase. For example, Systec series hydraulic injection moulding machines from Sumitomo (SHI) Demag are equipped with electrically adjustable DFEE type control pumps and high-efficiency drive motors. This is why noise level during operation of Systec 210, with 2,100 kN closing force and 560 mm bar width, reaches only 64 dB (A), is relatively low even in standard and is well below the industry standard of approx. 68 dB (A) sound pressure emission.
Hydraulic machines from Sumitomo (SHI) Demag generate even less noise when activeDrive drive concept is used. It reduces the sound pressure level of Systec 210 (2,100 kN closing force, 560 mm bar width) to 60 dB (A).
The innovative activeDrive drive concept from Sumitomo (SHI) Demag consists of a frequency-controlled high-performance motor and a hydraulic pump. Dynamic power adjustment to all cycle-dependent requirements ensures optimal efficiency because there is only as much power as required in each cycle sequence. This results in significant energy savings of 30 – 60 % and a noticeable, about half as high noise level.