Creating Contact Constraints

This task shows you how to apply a constraint with a relative positioning that can be compared to contact. You can either select the geometry or the command first.

This constraint can be created between either two elements. These constraints are in priority:

  • concentricity
  • coincidence
  • tangency

Use the contextual menu if you want to create other types of constraints.

Open the Constraint_Contact.CATPart document.
  1. Select Contact Constraint  from the Constraint toolbar (Constraint Creation subtoolbar).

  1. Click a first element. For example, click a circle.

  2. Click a second element. For example, click another circle.

The Concentricity constraint symbol appears and the constraint is created.


According to the elements you select, a single type of constraint is proposed for defining the contact:
  • A point and a line: coincidence
  • Two circles: concentricity
  • Two lines: coincidence
  • Two points: coincidence
  • A line and a circle: tangency
  • A point and any other element: coincidence
  • Two curves (except circles and/or ellipses) or two lines: tangency
  • Two curves and/or ellipses: concentricity  

Modifying or Deleting Contact Constraints

You can modify or even delete the contact constraint as follows:

  1. Make sure either Constraint or Contact Constraint is active in the Constraint toolbar.

  2. Right-click the constraint you want to modify or delete.

  3. Select the option corresponding to the desired operation, from the contextual menu. For example, select the Distance constraint type to turn the contact constraint into a distance constraint.
    The Distance constraint symbol and value now appear as shown here.