How to handle multiple constraints on parts?

一、 Model Preparation

Tolerance Analysis in Multi‑Constraint Systems
Effective tolerance verification requires evaluating not only assembly‑point deviations but also adjacent‑part interference and mechanical constraints. This case applies rotational constraints and conditional iteration to solve such multi‑factor challenges.

Probiem Statement

Can the outer‑edge variation of the lead piece be maintained within 1 mm under current tolerances and manufacturing processes?

Assembly process flow

Part tolerances

二、Assembly Steps

Step 1: Install the tapered pin onto the mounting base 

Assembly method: Single hole, single pin

Note: The tapered pin and the mounting base are fitted with a pin-hole connection, and the tapered pin also acts as a locking mechanism for the foot plate.

Step 2: Install the shaft onto the mounting plate 

Assembly method: Single hole, single pin

Note: The shaft is inserted from one end of the mounting base, first mates with the pin in the hole on the mounting plate.

Step 3: Assemble Shaft and Foot Piece

Assembly Method: Single‑hole, single‑pin 

Note: Install the shaft and foot piece onto the mounting base; then press the tapered pin inward to lock the foot piece securely in place.

Rotational Constraint Mechanism

During assembly from the rotating shaft to the mounting surface, the tapered pin interacts with the foot plate, causing the foot plate to rotate into its locked position.

Floating animation

Calculation results

三、Iterative Assembly

 Interference Elimination

Beyond locking the foot piece with the tapered pin, we also address potential interference between the foot piece's lower end and the mounting surface (upper stop shown below). Conditional constraints are applied to eliminate this interference during iterative assembly.

Iterative Assembly Workflow

Set Up Measurements：Define measurement points at the potential interference locations.

Enable Iteration：Activate the iterative assembly feature within the assembly settings.

Check & Validate：The assembly is considered valid only if the measured distance between stop surfaces is greater than zero.

Handle Interference：If interference is detected (measured distance < 0), the assembly reruns automatically until the condition is satisfied or the iteration limit is reached.

四、Results Comparison

Without the upper stop in the model, only 65.2% of outer‑end motion points stay within 1 mm.

Introducing the upper stop through iterative assembly removes non‑compliant cases, aligning the simulation with real conditions and increasing the acceptable‑motion rate.