How to Choose a Tunnel Drilling Machine

At Puhua Energy Equipment Technology (Shandong) Co., Ltd., we provide customized tunnel drilling machines and after-sales support for tunnel, hydropower, and mining projects in over 30 countries every year. Over the past decade, we have had in-depth discussions with hundreds of foreign procurement managers, chief engineers, and contractors. We have found that even experienced buyers can be misled by widely circulated myths in the industry. These misconceptions can range from simply wasting money to causing months of tunnel and project losses. Today, as a manufacturer, we want to clarify three of the most common misunderstandings.

Misconception #1: “A Heavier Tunnel Drilling Machine Is Always More Stable”

This idea sounds intuitive – heavier means better grip, less shaking while drilling. But the reality is more complex. The key indicator of a tunnel drilling machine’s stability is ground pressure (psi or kPa), not simply total weight. A 30-ton machine with narrow tires and a rigid chassis is more likely to sink, tilt, or even crush already-poured invert concrete on muddy or broken tunnel floors. In contrast, a well-designed 22-ton tunnel drilling machine – with wide, low-pressure tires (40% more contact area), oscillating axles, and a low center of gravity – can move smoothly over the same difficult ground.

We once responded to an Indonesian customer’s request by changing the original 28-ton configuration to 22 tons, while adopting wide low-pressure tires (ground pressure reduced to 0.08 MPa), oscillating axles, and a lowered center of gravity. The result: excellent traction and stability on the same poor tunnel floor, plus 18% lower fuel consumption. So next time a supplier emphasizes “our machine is extra heavy,” ask them: “What is your static ground pressure? What is the maximum allowable ground pressure on C30 concrete pavement?” A supplier that cannot give a straight answer is likely hiding design flaws.

Misconception #2: “Higher Hydraulic Pressure Means Stronger Drilling Performance”

Many foreign buyers instinctively think “280 bar is better than 220 bar” when comparing technical parameters. This mistakes hydraulic system pressure for drilling capacity. In fact, a rock drill’s drilling capacity depends on impact power, where impact power = pressure × flow × piston design efficiency × shock wave quality. A well‑designed rock drill can achieve higher single‑impact energy and faster penetration at lower system pressure by optimizing piston stroke, impact frequency, and return backpressure control.

Internally at Puhua Energy, we kept the record of a real‑life comparison test. At a hydropower diversion tunnel in Myanmar (rock hardness 160–190 MPa), the customer tested our PHC‑80 tunnel drilling machine against a competitor’s unit rated at 280 bar. Our system pressure was only 225 bar, but we delivered 380 joules of impact energy per blow. The competitor’s machine, despite higher pressure, only achieved 320 joules per blow, with a seriously trailing shock wave that turned much of the energy into vibration and heat. The result: our drilling speed was 22% faster, and our drill bit life was 30% longer. Therefore, we strongly recommend that all foreign buyers ask suppliers for measured impact energy (joules per blow) and specific energy (hydraulic power consumed per meter drilled) – not just the pressure gauge reading.

Misconception #3: “All Spare Parts Can Be Bought Online, So a Local Agent Isn’t Needed”

This is the most dangerous and costly misconception. A tunnel drilling machine contains thousands of parts, of which about 60 to 90 are custom precision‑machined components: rotation bushings, coupling sleeves, front cylinder bodies, chuck jaws, oil distribution rings, impact pistons, and more. These parts require special materials, heat treatment, and tight geometrical tolerances. You absolutely cannot buy them from a general hydraulic website or a local hardware store. We have witnessed too many tragedies where buyers tried to “save money by skipping the agent” and ended up with months of downtime.

Here is an example: last year, a long‑time customer in West Africa bought a used machine through informal channels. After two months, the coupling sleeve broke. He searched every machine shop in the capital – no one could machine an internal spline to DIN grade 7 or provide a qualified carburized layer. He then urgently contacted us at Puhua Energy. Although we were very willing to help, the machine was not our product and the original manufacturer no longer supplied parts. The only solution was to replace the entire rotary head assembly – costing $17,000, with 10 days of air freight. Meanwhile, project downtime cost over $60,000.

As a responsible manufacturer, Puhua Energy Equipment Technology adheres to the following principles:

(1).Maintain safety stock of all critical spare parts in our regional warehouses (Singapore, Dubai, Hamburg).

(2).Promise to ship any downtime‑causing part within 48 hours, otherwise compensate on a daily basis.

(3).Use ISO standard seals and hydraulic components as much as possible during the design phase, reducing the proportion of exclusive custom parts.

Our sincere hope is that buyers understand: a professional local agent and spare parts system is not a cost item – it is your insurance policy.

An Honest Word from the Supplier

Puhua Energy Equipment Technology (Shandong) Co., Ltd. is never afraid of detailed questions. In fact, when a procurement manager asks us for MTBF (Mean Time Between Failures) data, failure mode analysis reports, or overhaul records from the last two years, we know we are dealing with a truly knowledgeable partner who wants a long‑term relationship. We will provide all this material without reservation, and even invite them to visit our factory in Shandong to see the production process and talk face‑to‑face with our assembly team leader. Because a reputable manufacturer has nothing to hide.

Frequently Asked Questions (FAQ)

Q1: Can the equipment be customized according to site conditions?

A: Yes, we support full customization. Based on your project’s geology, tunnel dimensions, construction schedule, and power/fuel preferences, we can tailor the drill rig’s power, drilling depth, travel system, and automation level to create a machine that perfectly matches your working conditions.

Q2: How do you ensure safe packaging and transport for export?

A: The equipment is packed with heavy‑duty anti‑rust protection and securely braced. It is suitable for long‑distance sea or land transport, eliminating the risk of scratches or corrosion during shipping. We also track logistics from start to finish.

Q3: Do you provide after‑sales maintenance and technical support for overseas buyers?

A: Absolutely. We offer multilingual remote technical guidance, operation training, and troubleshooting support. We keep a stock of genuine original spare parts ready for fast cross‑border delivery. In addition, we provide a detailed daily maintenance manual to reduce repair difficulty at overseas sites.

Q4: What if I don’t understand the technical parameters – can your team help me choose the right model?

A: Yes, we provide free one‑on‑one model selection assistance. Our professional engineering team will consider your construction environment, drilling requirements, and budget to help you avoid common selection mistakes and recommend a highly suitable, cost‑effective tunnel drilling machine solution. No more blind purchasing and wasting money.