Va. Code Ann. § 58.1-3508.3

Machinery and tools used directly in the manufacture of precision investment castings shall constitute a classification for local taxation separate from other classifications of machinery and tools, as defined in § 58.1-3507. The governing body of any county, city, or town may levy a tax on such classification of property at a different rate from the tax levied on other machinery and tools. The rate of tax and the rate of assessment shall not exceed that applicable generally to machinery and tools.