CNC (computer numerical control) Horizontal boring machines (HBM) are used to perform drilling and milling operations on large workpieces, typically in industrial and heavy engineering applications. Here are ten manufacturers that are well-known for producing CNC Horizontal boring machines:

1. Giddings & Lewis (a division of Fives Group)
2. WFL (WEMA Werkzeugmaschinen GmbH Leipzig)
3. UnionChemnitz
4. TOS Varnsdorf a.s.
5. PAMA S.p.A.
6. PROMPT & CO
7. Zayer S.L.
8. Doosan Infracore
9. Niles-Simmons-Hegenscheidt GmbH
10. Skoda Machine Tool

This list is not exhaustive and in no particular order. It is based on market share, reputation and industry standards in specific countries and industries. Additionally, depending on the specific type of CNC Horizontal Boring machine (ex: Table type, Floor type, and so on) the ranking can vary and some other manufacturers like Toshiba Machine, Lucchini RS S.p.A,..etc. could be added to the list.