3D Scantech: Full-field 3D Scanning of Large-Volume Casting to Identify Allowance for Machining

It is critical to control machining allowance to ensure precise machining for castings strictly. An insufficient machining allowance makes it difficult to remove residual materials from the previous process.

An excessive allowance will lead to an increased machining workload and more consumption of materials, tools, and energy.

Scantech is a high-tech 3D scanner manufacturer offering products such as 3D laser scanners, 3D body scanners, and automated 3D measurement systems. We are dedicated to improving your business by providing efficient 3D solutions.

In this application story, we will show you how to capture full-field data of a large-scale casting and identify its allowance for further machining. The equipment we use is TrackScan-P, a non-contact 3D scanner for large objects.

Optimization of Casting Machining

Dongfang Turbine Co., Ltd. of Dongfang Electric Corporation is a high-tech enterprise engaging in the research, design, and manufacture of large power station equipment.

The company’s products include coal-fired steam turbines, nuclear steam turbines, gas turbines, turbine retrofitting, servicing, industrial turbines, new materials, and new energy products.

The customer was looking for options to optimize casting machining. By 3D scanning the casting and comparing it with the CAD model, they aim to analyze whether there is sufficient allowance for further machining.

If there is no allowance at some surfaces, they need to analyze whether it is feasible to conduct fitting to ensure these surfaces can be machined later. If the former way doesn’t work, customers need to identify the areas thinner than the allowance and determine the amount for repair welding.

After the inspection, the data captured will serve as a reference for virtual marking and locating the machined datum for the CNC machine.

The casting in this case is a steam exhaust hood. It is relatively large with a diameter of around 6 meters. It is required to conduct full-field scanning and determine the marking for the machining datum and marking for 20 holes.

Pain Points of Traditional Manual Marking

The customer used to mark castings manually based on empirical estimation to check whether there is sufficient allowance and locate the datum.

This traditional and manual method is inefficient and fails to find the best datum. Every time the operators adjust the position of the part, they need to restart and find a new datum, which is time-consuming.

By virtual marking in an accurate 3D model, users can identify the precise allowance of parts for marking. Manual marking, compared with virtual marking is much less accurate.

Therefore, some qualified products may be deemed as unqualified or defective, resulting in increased manufacturing costs.

How 3D Scanning Help in Casting Manufacturing

To shorten its cycle time, the company reached Scantech seeking help for identifying the allowance, optimizing marking, and accelerating machining for casting.

The following steps show how Scantech’s 3D solution help in this project.

Step 1: Scan (about 1 hour)

Using the optical tracking 3D scanner TrackScan-P, the engineer scanned the full-field data of the casting and obtained its actual 3D model.

Step 2: Comparative analysis (about 10 minutes)

The data captured helped them understand where deviations occurred in the casting. The engineer quickly compared the scan data with the CAD model and analyzed the results with 3D software:

• Check whether there is a sufficient allowance;
• For the areas where allowance was sufficient, the data was used to locate the optimal machined datum.
• For the areas where allowance was insufficient, they located the areas that needed to be repaired and identified the amount of repair welding.

Step 3: Marking (about 2 hours)

Using the software, they simulated the marking before drawing lines on the castings. This helped the customer calculate the marking location accurately and caught any potential problems. The engineer marked the casting as well as the holes that need to be processed based on the analysis.

Step 4: Machining

Establish accurate data for machining as well as the positions of holes.

Features of Scantech’s 3D solution

Scantech’s optical measuring system TrackScan-P consists of a 3D laser measurement scanner, engineered with innovative blue-and-red laser scanning, and an optical and sticker-free tracker.

The system measures the actual geometry of the blank, which ensures sufficient machining allowance in production and replaces traditional marking. It provides the data basis for adaptive machining by optimizing the machining path based on the data captured.

Ergonomic Design of 3D scanner

• The portable 3D scanner can scan the part from any direction you want, which is easy to operate.

• The 3D scanner is built onto a spherical frame, which offers an even stress distribution. The markers placed over this soccer-like frame enable E-Track to position the 3D scanner in all directions.

• It’s made of aerospace fiber so it is lightweight. Due to its ergonomic design, the 3D scanner allows users to scan for a long scanning session with minimal wrist fatigue.

• It is seldom affected by temperatures and ensures steady performance.

Practice-oriented Design of E-Track

• The E-Tracker features a dual-camera system with a distance of 900 mm between cameras, which allows large-volume tracking.

• Thanks to the dynamic tracking of E-Track (the optical tacker of the TrackScan-P measurement system), it can identify the position of the 3D scanner in relation to that of the part freely, which greatly improves the non-contact 3D scanning efficiency. It also boasts a smooth performance as it can be operated regardless of vibrations.

Wireless and Portable CMM T-Probe

• Wireless T-Probe comes with probes of different lengths. Using a portable T-Probe, they can conduct contact measurements and obtain high-precision 3D data quickly. It means they can check the accuracy of marking by just probing it.

Project Significance

• The 3D laser scanner can scan the full-field data of the parts. Users can analyze the machining allowance quickly and set up the machining according to which improves production efficiency.

• The solution helps to identify the area where repair welding is needed, reducing the defective rate of products and decreasing the costs.

• The efficiency of marking is enhanced by virtual marking in the software.

• The machined datum is adjusted according to the analysis to ensure every surface to be machines has a sufficient allowance. It contributes to reducing the reject ration of

• It was beneficial for manufacturers to ensure the parts machines could conform to the specifications required.

This content was first published on the 3D Scantech website.