Lenz - The Specialist for Ground Joints

The Lenz® range of ground joint instruments
With decades of experience, advanced technological know-how and the outstanding properties of DURAN® glass we guarantee the proven quality of our precision ground joints.

The Lenz® range of ground joint instruments includes conical joints, stopcocks, ground joint flasks, separating and dropping funnels as well as a large range of ground joint components.

Quality with system
Lenz® ground joint instruments are produced according to the standard DIN 12242 / ISO 383. Each production step is tested by a quality management system, based on DIN ISO 9001 / EN 29001. The tests are examined by a cone measuring device for checking the taper, a surface roughness meter for testing the roughness parameters and a wall thick­ness measuring apparatus with a magnetic inductive measuring process to guarantee a homogenuos concentricity and wall thickness.

A multiple-station unit serves for grinding as well as for pre- and post-polishing of our ground joints. An electro-mechanical scanner ensures constant quality. In cases of specific high demands on function and precision the grinding is processed by hand.

Production of ground joint workpieces made of DURAN® tubing on fully automatic glass forming machines.

The follow-up processing of NS cones on half- automatic circular grinding machines.

The pre- and post-polishing of NS sockets takes place on multiple station grindig machines.

Conicity testing: the accuracy of the ground joints is validated by highprecise cone measuring devices.
Product features
High taper accuracy of the cones
Precise concentricity
Small roughness of the surface
Excellent tightness
Minimized need for grease
No bend out of line

Our ground joint instruments are marked
with the Lenz logo and indicate the
respective size of the ground joint.
Conical ground joints
acc. to DIN 12242/ISO 383

Nominal size
Ø1 (mm)Cone/
Ø2 (mm)Length
5/13 5 3,6 13
7/16 7,5 5,8 16
10/19 10 8 19
12/21 12,5 10,3 21
14/23 14,5 12,1 23
19/26 18,8 16,1 26
24/29 24 21 29
29/32 29,2 25,9 32
34/35 34,5 30,9 35
45/40 45 40,9 40
60/46 60 55,3 46
71/51 71 65,8 51
85/55 85 79,4 55
*approximate measures