A rubber compound factory at Alston Road, in Keighley -- which employs 68 people -- is set to close in July.
Parent company Watts Industrial Polymers, which acquired the Ondura rubber company for £5.5 million less than two years ago, is currently consulting with employees and trade unions about a phased reduction in activity before the planned closure.
It is hoped some workers may be re-deployed.
Watts managing director Stewart Charters said: "Unfortunately, a downturn in the marketplace and the historical lack of investment in the plant means that we cannot see a viable business for the future operating from this site.
"It is very sad and we regret it."
President of Keighley Trades Union Council Steve Davison said: "We are shocked to hear about the closure of Ondura Keighley, a site we have always understood to be the most profitable part of the operation.
"It's well known that we have campaigned to improve working conditions, there which have been the worst in Keighley. Nevertheless, with the decline in manufacturing in the town, we wish to preserve every job.
"Should workers at Ondura or members of the GMB trade union decide to oppose the closure and campaign to keep the factory open, then Keighley TUC pledges its full support."
Production of Ondura unvulcanised rubber sheets at the Castlefields estate, in Bingley, would be unaffected, he added. The sheets are primarily used as sidewall veneer for the re-tread tyre industry.
The Keighley plant became part of the Watts Industrial Group as part of its acquisition of assets from Wellington Holdings, in October 1999. Watts Industrial Polymers was formed at the same time, when Ondura and Hatcham Rubber Ltd were combined with the group's existing compounding division.
Watts is the UK rubber industry's largest custom compound provider of natural and synthetic rubber, serving the automotive, construction and general engineering markets.
Ondura has a long association with the town, having been founded in 1923 by Herbert V Jackson.
By 1929 it was supplying government departments, nationalised industries, public transport authorities and fleet operators, and later went on to export tyres throughout the world.
In 1969 it opened a factory at Cross Hills, specialising in large tyres for earth movers and agricultural equipment, and at that time employed around 350 people.
The Cross Hills factory closed in 1980 and three years later the Keighley plant employed only 40 staff.
Ondura was a founder member of the Retread Manufacturers Association in the mid 1940s.
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