Ian Spicer, from Hartcliffe, was using a CNC machine at Mil Tu Fit Engineering last August when a metal bar flew out of the machine and hit him in the head.
As a result of the incident, the 34-year-old suffered a compressed skull fracture, wide gashes to his chest, a dislodged breast place, a broken wrist and other minor injuries, Bristol Crown Court was told.
The court was told that the employer had failed to put guards in its machines which resulted in the employee suffering serious head and chest injuries.
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Mil Tu Fit was prosecuted by the Health and Safety Executive (HSE) who found that the firm had two CNC lathes on the premises, one for processing short parts only and the other with a bar feed attachment and guard, which was specifically used for longer machining parts.
Due to the fact that the machine for longer parts was already being used, Mr Spicer was told by his manager to use the other lathe, without the bar feed attachment, to machine long metal bars which were over 2.5 metres in length.
Furthermore, the court was informed that the worker was told to put up a barrier of empty drums at the end of the machine to help protect the rotating bar from other workers, a practice which the firm had used on a number of occasions.
When the worker was using the machine, the bar became unstable, bent under its own weight and hit Mr Spicer, who was thrown to the ground and knocked out.
HSE inspector Mehtaab Hamid stated after the verdict that despite the fact that Mr Spicer had gone back to work after the incident, he was not put in his previous role as a machine operator and was only part-time.
'Some nine months after the incident, Mr Spicer is still suffering from severe headaches, chest, back and joint pains, as well as dizziness and flashbacks. At this point, his work future is uncertain,' Mr Hamid stated.
'Had the company used the appropriate equipment which was available on site, this incident could have been avoided and Mr Spicer would not have suffered these terrible injuries,' he further added.
Mil Tu Fit Engineering was found guilty of breaking the rules with regards to the Provision and Use of Work Equipment Regulations.
The company was fined 10,000 and was ordered to cover the costs of the case which amounted to 3,632.