All Sill's employees will be retained as part of the acquisition, while Hoffmeister bosses Oliver Hoffmeister and Jens Hanfland will take over the management of Sill.
'We want to comnbine the established strengths of both companies in national and international business to create a strong unit,' said Oliver Hoffmeister (pictured).
Sill's product portfolio will add a large number of luminaires to Hoffmeister's exterior lighting range, Hoffmeister said, and the company will be making a 'major investment' in new technologies, including LEDs.
'Sill is a strong brand with innovative solutions at a very high technical level,' said Jens Hanfland. 'The highly committed and professionally trained employees are a key success factor.'
Oliver Hoffmeister said: 'Hoffmeister will benefit from the extensive vertical production integration at Sill and will be able to considerably extend its capacities, particularly in sheet metal processing.'
Sill had been in difficulties since the start of the year, having struggled with the transition to LEDs.