Quality control of PDC cutters

The PDC cutters consist of a Polycrystalline Diamond layer and carbide substrate. PDC cutters are also named Polycrystalline Diamond Compact cutters, which is a kind of super hard material. The use of polycrystalline diamond compact (PDC) cutters is widely spread nowadays due to their high performance and durability in harsh environments.

The critically important things for PDC cutters in oilfield drilling application are quality and consistency. I believe everyone will agree. But how to control the quality?

To ensure every piece of PDC cutter comes to ZZBETTER customer’s hands with high quality, ZZBETTER has established a strict quality control system, including raw material control, production process control, and finished products control. Our worker is highly trained and very professional and dedicated. Each PDC cutter is built with highly trained operators and pressure is controlled in presses during sintering.

PDC cutter quality control：

1. Raw material

2. Production process

3. Inspection of finished products

     1. Raw material control

1.1 For making the PDC cutter oilfield drilling application we use the imported diamond. We also have to crush and shape it again, making the particle size more uniform. We also need to purify the diamond material.

1.2 We use the Laser Particle Size Analyzer to analyze the particle size distribution, purity and size for each batch of diamond powder.

1.3 For tungsten carbide substrate we use the right grade with high impact resistance.

    2. Production process

2.1 We have professional operator and advanced facilities to produce the PDC cutters

2.2 During the production we will check the temperature and pressure in real-time and adjust in time. The temperature is 1300 - 1500 ℃. The pressure is 6 - 7 GPA. It’s HTHP pressing.

For producing one piece of PDC Cutters will need around 30 minutes in total.

For every batch of PDC cutters, the first piece is very important. Before the mass production, we will inspect the first piece to see whether it meets the customer's requirements for dimension and performance. 

3.Inspection of finished products

To ensure all PDC cutters qualified and consistent, we should not only strictly control raw materials inspection and production flow control and technique improvement, we also should committed to build up a laboratory with advanced testing facilities to imitate oilfield drilling conditions and test PDC cutters at factory before deliver to our customers.

For finished product control we will do from below aspects:

Size and appearance inspection

Internal defects control

Performance test

3.1 Size and appearance inspection: diameter, height, diamond thickness, chamfer, geometric sizes, crack, black spot, etc.

3.2 Internal defects control

For internal defect control we will use the advanced imported ultrasonic C-san inspection equipment. For oil filed PDC cutters we have to scan every pieces.

With C-scanning system, ultrasonic wave could penetrate PDC layer and detect its delamination or cavity defect. C-scanning system could find out size and position of defects and show them on PC screen. It’s will take around 20minutes to do one time inspect.

3.3 PDC Cutter’s performance sampling test:

wear resistance

impact resistance

thermal stability.

3.3.1 Wear Resistance Testing: by measuring how many weights lost after PDC cutters ground the granite in a certain period of time, we get a wear-off ratio. It’s the mass loss between the PDC cutters and granite. The higher the ratio, the more wear resistance the PDC Cutters will be.

3.3.2 Impact Resistance Test: We also call it Drop-Weight test, using a vertical lathe at certain height hammering onto PDC Cutter cutting profile, usually with a certain degree (15-25 degree) slide. Weights of this vertical lathe and its preset height would indicate how impact resistant this PDC cutter would be.

3.3.3 Thermal Stability Test: It’s aimed to test if PDC Cutters are thermal stable enough under high temperature working conditions.  At laboratory, we put PDC cutters under 700-750 ℃ in 10-15 minutes and inspect diamond layer condition after natural cooling in the air. Usually this process would accompany with another wear resistance and impact resistance to compare PDC cutter’s quality before test and after test.