Product Detailed Description
The HSK125A-MLD20-135 Toolholder is a specialized clamping system engineered for heavy-duty drilling and reaming operations in CNC Vertical Machining Centers (VMCs) and Horizontal Machining Centers (HMCs). It combines the stability of the HSK125A dual-contact taper interface with the precision of an MLD20 Morse taper drill chuck-designed exclusively to secure Morse taper shank tools (e.g., large-diameter twist drills, reamers, core drills). With a 135mm overall length, it balances deep-hole reach and structural rigidity, making it ideal for industries like heavy machinery manufacturing, oil & gas pipe machining, and automotive engine block drilling, where high torque and minimal runout are critical.
Core Design & Engineering Advantages
HSK125A Dual-Contact Taper Interface
Complies with ISO 1940-1 standards, featuring a hollow 1:10 taper with simultaneous taper + face contact (dual-location). This eliminates radial runout (≤0.005mm at 3×D from the chuck end) and axial slippage, even under high drilling torque (up to 250 N·m). The design ensures consistent tool concentricity-essential for maintaining hole roundness (IT7-IT8 grade) in thick-walled workpieces (e.g., 50mm+ steel plates).
MLD20 Morse Taper Drill Chuck Function
The "MLD20" designation denotes a Morse taper drill chuck optimized for Morse Taper No. 2 shank tools (common for drills with 13-25mm diameter). It uses a self-locking taper mechanism (no additional setscrews) to achieve high clamping force (up to 10kN), preventing tool slippage during high-torque drilling of cast iron (HT300) or alloy steel (40Cr). Unlike ER collets, the Morse taper interface distributes stress evenly across the tool shank, reducing shank deformation in deep cuts.
135mm Optimized Length
The 135mm overall length (from HSK taper reference face to chuck end) provides sufficient reach for deep-hole drilling (up to 80mm depth, depending on tool length) while avoiding excessive overhang. This balance minimizes vibration- a key issue in long-reach drilling-and maintains tool rigidity, even when machining workpieces with complex geometries (e.g., engine block oil passages).
Heavy-Duty Construction
Machined from heat-treated 42CrMo alloy steel, quenched and tempered to HRC 45-50. The material's high tensile strength (≥1,050 MPa) and impact resistance withstand repeated tool clamping cycles and shock loads (e.g., drilling through casting sand inclusions). A black oxide coating enhances corrosion resistance, protecting against coolant damage in long-term use.
Optional Through-Coolant System
Available with integrated 4mm-diameter coolant channels that direct high-pressure coolant (up to 20 bar) through the chuck to the tool's internal cooling holes. This feature flushes chips from deep holes and reduces thermal wear on carbide drills, extending tool life by 35% when machining stainless steel (304/316) or high-temperature alloys.
Model Breakdown
| Model Segment |
Definition |
| HSK125A |
HSK taper size: 125mm nominal diameter, A-type (hollow, 1:10 taper ratio) |
| MLD20 |
Morse Taper Drill Chuck: adapting Morse Taper No. 2 shanks, clamping range 13-25mm |
| 135 |
Overall length: 135mm (from HSK taper reference face to chuck end) |
Machine & Tool Compatibility
-
- CNC Machines: Fits HMCs/VMCs with HSK125A spindles (e.g., Mazak FH-8800, DMG MORI HSC 70 linear, Haas VF-12).
- Cutting Tools: Designed for Morse Taper No.2 shank tools, including:
- Twist drills (13-25mm diameter)
- Core drills (for rough holemaking)
- Reamers (H7-H8 hole tolerance)
- Counterbores (for recessed holes)
Application & Compatibility
The HSK125A-MLD20-135 is purpose-built for Morse taper shank drilling tools-addressing the needs of heavy-duty holemaking:
- Large-Diameter Drilling: Clamps 20mm Morse No.2 shank carbide twist drills for drilling 50mm-deep holes in S45C carbon steel structural components, with low runout ensuring hole straightness (≤0.02mm/m).
- Cast Iron Machining: Secures Morse taper core drills for roughing 30mm-diameter holes in HT300 gray iron pump housings, leveraging the self-locking chuck to handle sand-induced shock loads.
- Precision Reaming: Holds Morse taper reamers (H7 tolerance) for finishing 25mm-diameter holes in 40Cr alloy steel hydraulic cylinders, maintaining hole surface finish (Ra ≤0.8μm).
- Oil & Gas Pipe Drilling: Adapts to Morse taper drill bits for drilling 22mm-diameter holes in thick-walled carbon steel pipes (API 5L), with through-coolant preventing chip clogging.
User Benefits
High Torque Capacity: 250 N·m maximum torque enables heavy-duty drilling of thick materials, replacing slower manual drilling processes.
Precision Hole Quality: ≤0.005mm radial runout ensures hole roundness and straightness, reducing post-processing (e.g., honing) by 50%.
Deep-Hole Capability: 135mm length provides sufficient reach for 80mm-deep holes, eliminating the need for extended-length toolholders that cause vibration.
Durability: 42CrMo steel and black oxide coating ensure 3+ years of service in high-volume production, backed by a 12-month warranty against manufacturing defects.
Technical Specifications
| Parameter |
Specification |
Application Impact |
| Taper Interface |
HSK125A (ISO 1940-1, 1:10 taper) |
Dual-contact for low runout |
| Chuck Type |
MLD20 Morse Taper Drill Chuck |
Clamps Morse No.2 shank tools (13-25mm) |
| Overall Length |
135mm |
Deep-hole reach + rigidity balance |
| Material |
42CrMo alloy steel |
Withstands high torque/shock loads |
| Hardness |
HRC 45-50 |
Wear resistance for repeated clamping |
| Radial Runout |
≤0.005mm (at 3×D from chuck end) |
Ensures hole roundness (IT7 grade) |
| Maximum RPM |
4,000 rpm (balanced to G2.5 standard) |
Safe for medium-speed drilling |
| Maximum Torque |
250 N·m |
Suitable for heavy-duty drilling |
| Coolant Compatibility |
Optional through-coolant (20 bar max) |
Chip evacuation in deep holes |
Why Choose Us?
"Engineered for Flawless Flat Surfaces" - Trusted by 1,000+ CNC workshops globally.
Certifications: ISO 9001
| MATERIAL |
GRADE |
ISO |
COATING COMPOSITION |
COLOR |
| Steel P |
YP9117 |
P10-P20 |
TiCN+α-Al2O |
YELLOW |
| YP9112 |
P10-P25 |
TiCN+α-Al2O |
BLACK |
| YP9127 |
P15-P30 |
MT-TiCN+α-Al2O |
YELLOW |
| YP9122 |
P15-P30 |
MT-TiCN+α-Al2O |
BLACK |
| YP9132 |
P25-P40 |
MT-TiCN+α-Al2O |
BLACK |
| YP9115 |
P10-P20 |
TiN+MT-TiCN+Al2O+Tin |
DOUBLE COLOR |
| YP9125 |
P15-P30 |
TiN+MT-TiCN+Al2O+Tin |
DOUBLE COLOR |
| GRADE |
ISO |
COATING COMPOSITION |
COLOR |
| YG2125 |
P10-P3
M15-M30
K15-K30 |
TiALN |
GREY BLACK |
| YG2125B |
P10-P30
M15-M30 |
TiALSiN |
DARK PURPLE |
| YM2127 |
M10-M30 |
TiALN |
YELLOW |
| YS6125 |
P10-P30
M15-M30 |
TiALN |
SILVER |
| YM6110 |
M10-M30 |
TiALN |
DARK PURPLE |
| YM6120 |
M10-M30 |
TiALSiN |
COPPER |
| YM6125 |
M10-M30 |
AlCrN+AlCrSiN |
YELLOW |
| Carbide turning inserts |
TNMG/WNMG/CNMG/DNMG/VNMG/SNMG/CCMT/TCMT/VBMT/DCMT |
| Carbide threading inserts |
16ER/16IR AG60 AG55 /ISO1.0 1.5 2.0 2.5 TR SAGE API APIRD W ect |
| Carbide grooving inserts |
MGMN/MRMN/TDC/TDJ/TDT/TDXU/SP/DGN/N123/PENTA |
| Carbide milling inserts |
R390 /APMT/ APKT/BDMT/RCKT/RPMW/RPMT/RDMT |
| High feed milling inserts |
BLMP/LNMU/LOGU/SNMX/ONMU/3PKT/LNMX/WNMU/SDMT |
| Aluminum inserts |
CCGT/DCGT/TCGT/VCGT/GDMA/SEKT/APKT |
| Drilling inserts |
SPMG/WCMX |
| Cermet cutting tools |
CCGT/TPGT/WBGT/TNGG |
| Toolholders |
SER/SNR/MGEHR/L/SPB ect |
Our company has sufficient stock, and we also provide non-standard customised service,different Hardness based on client's requirement.
Packaging:
Step 1:The product is packed in a plastic box, normally 10 pcs in a box.
Step 2: using bubble wraps to package each insert parcel.
Step 3: using the paper carton of Thickening and hard with bubble wraps to sealing.
Shipping:
We use the fastest express (FedEx, TNT, DHL, UPS) to deliver, can deliver to any country within 5-15 days.
T/T / Western Union
1Q:Who are we?
A:We are based in Chengdu, China. The company locates in Chengdu City, one of the big cutting tools production base in China. Now we have over 50 employees and passed the ISO 9001:2008 certification. Our products have been exported to Europe, Southeast Asia, Middle East and other areas for more than 5 years.
2Q:How can we guarantee quality?
A:Always a pre-production sample before mass production;Always final Inspection before shipment.
3Q:What can you buy from us?
A:carbide turning milling threading grooving&parting drilling inserts, End mills, tiny tools, toolholders, swiss tools and so on; For more information, please contact us.
4Q:Can I get a sample to check your quality?
A:Yes, after confirm the price, you can require sample to check the quality. we will send you samples when you pay for them.
5Q: what services can we provide?
A:Delivery Terms: FOB, CIF, EXW, FCA, CPT, Express Delivery;
Payment Currency :USD,EUR,RMB;
Payment Type: T/T, Western Union;
Language Spoken: English, Chinese,
Stock : Standard specification within 24 hours delivery
Our Advantages:
1.A large number of standard stocks, the spot is fast.Provide 24-hour pre-sales and after-sales service, reply within 3 minutes.
2. Manufacturer with more than 15 years experience.
3. A great quantity of formula special for all kinds of different stone.
4. Approved quality with factory competitive price.
5. Long lifespan, good sharpness, stable performance and high cutting efficiency.
6. Custom-design can be meet upon request, small trial order available any time, sample for testing can be delivery in very short time.
7.Welcome friends from all over the world to contact, let us cooperate and win-win.
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