The Bolzoni Auramo Group is a leader in Europe and one of the two most important producers in the world of fork lift truck attachments.
Bolzoni Auramo is a benchmark for all companies working in material handling, thanks to the largest range of attachments and the knowledge of the customer’s particular industrial applications.
W orldwide market needs are answered with the highest quality levels through the use of technological innovation, sophisticated planning systems and the use of world class materials.
The New Challenge
Today, Bolzoni Auramo is in the business of forks for lift trucks and material handling in general, with an absolutely innovative production line in terms of quality and automation.
The Bolzoni R&D Department, strongly focused on product innovation, has employed the most advanced technologies and software for fork design.
Fork Drawings: Heel Heel shape: an increased heel section has provided improved resistance and low level of wear in the area subject to higher stress
Fork Drawings: Hooks Hooks width: smaller than forks.
Fork Drawings: Blade tapering Tapering of the blade: according to forks length and thickness
The material chosen is a micro-alloyed boron steel type 33MnCrB5, which
presents the following characteristics:
Good resistance to wear and corrosion (thanks to Manganese and Chromium)
Higher mechanical characteristics with notch bar impact test >40 Joules at T =-20°C, compared with ISO 2320 Standard establishing V-Charpy =27 Joules at T =-20°C
Excellent hardenability even on very thick parts (due to the presence of boron)
Good weldability due to low Carbon percentage
Available on the market and low-cost (absence of costly alloy elements such as Nichel and Molybdenum)
For every casting batch , the supplier delivers
the material Certificate with chemical composition,
decarburization, degree of pureness, values
of mechanical tests after heat treatment and
Note: Prof. P.Antona, lecturer in “Metallurgic Plants” at the Ferrara University and the Milan Polytechnic, has collaborated in setting up the manufacturing cycle
Technical Characteristics of the Production Process
The manufacturing cycle has been developed according to the following
High product quality and reliability (mechanical and metallurgic characteristics)
High automated production process guaranteeing efficiency and flexibility according to the “one piece flow” logic
Fast process cycle: lead-time 6-10 hours, depending on the fork section
Transformation cycle with low global energy content
Environment-friendly and ergonomically developed work conditions
Product traceability thanks to the Central Supervision and Control System
The manufacturing cycle is divided into the following phases:
1. Bar cutting, blade tapering and tip shaping
2. Induction heating and hot bending in a closed die with upsetting of the heel
3. Hardening and tempering heat treatment
4. Welding of the fixing hooks
5. Magnetic Particle Crack Detection
6. Shot blasting, painting and assembly
The Production Process
Raw Material Stock
10-12 metre long bars are stocked in a covered area.
Double U-brackets on the floor
Housing for up to 30 profiles with different sections
Raw material traceability thanks to the material casting number linked
with raw material batch
Transfer by means of internal/external bridge crane
Bar cutting, Blade tapering and Tip shaping
The production process starts with the bar cutting to obtain the right fork length and then blade tapering.
To obtain the fork tip shape, bars are then
conveyed to a Flame Cutting station, equipped with:
n° 2 vertical motorized trolleys and flame-cutting head
Control and management system with the possibility of handling predefined shapes.
The system can interface with the CAD-CAM, for optimized management of the entire work cycle.
Heating the bending area
The induction heating equipment characteristics are:
Automatic handling line and heating of the middle section of the bar up to 1100°C
N° 3 heating stations in sequence with 3 tunnel type inductors for even heating at the core (1100+/-20°C)
Automatic system for quick change of inductors
Bars are moved to the induction heating equipment, for the bending area heating before the hot stamping.
Hot bending and upsetting
The heel upsetting is obtained in a closed die
with a complete control on the shape and the
steel fiber disposition.
Special independent double pillar hydraulic 1600 ton press
Special closed die, multi-effect for bending and upsetting the heel
Side limit inserts variable according to the fork thickness
Automatic system for loading and positioning the bar on the die
Blowing nozzles to remove mill-scale before bending to avoid inclusion in the heel
Hot bending and upsetting
Press unloading & Furnace loading An industrial robot with articulated arm unloads the bended forks from the press and transfers them on a load system taking it into the hardening station.
Hardening and tempering
Forks are then transferred to the hardening and tempering phases, made up of the following stations:
1 Continuous gas heated hardening furnace with automatic cast link
1 Polymer quench tank, specially engineered to limit distortions during the cooling phase
1 Continuous gas heated tempering furnace with parallel chain conveyor belt
Full heat treatment with hardening and tempering on the entire fork grants
the best quality and reliability characteristics.
Hook Welding Station
1 Robot for unloading after heat treatment, grinding of the fork back in the hooks welding area and for loading/unloading of the welding station. For the unloading phase, the Robot receives information concerning fork recognition and positioning through a visual system
1 Tack-Welding Robot
1 Hook stockage area, equipped with
a device for single output of the pieces, which is completely automated
2 Robots for upper and lower hook welding
After the hardening and tempering phase the fork is transferred to the hook welding station, including:
2 immersion tanks for 2 principal water-based colors
1 spray booth for secondary water-based colors
Paint drying in a convection furnace by forced circulation of warm air
The shot blasting treatment eliminates the impurities and prepares the surface for painting.
Assembly of Hook Pins The last phase of the production process is the manual assemly of the hook pins.
Central System of Supervision and Control
The plant and the production process is supervised
through a Central System of Supervision and Control
The supervision software includes:
Handling of the production programs
manually keyed-in by the operator
according to a ‘menu’ method
Handling and sending the “missions”
to the various operating units in the installation
Number of forks produced calculated according to each single machine, handling line and total for the line.
Full traceability of every fork during every single production cycle and quality control. Possibility of displaying and printing the production parameters and quality controls for every step, from raw material till final product.
International Standards of reference for every fork:
Hook-on type fork arms and fork arm carriages
Technical characteristics and testing
Fork arms for lift trucks equipped with ISO fork carrier
Fork hooks, positioning locks
The excellent quality level is ensured by the tests and checks during the
whole production process following a specific Fork Quality Control Plan:
Controls made by bar Suppliers for every casting batch
for every batch the supplier delivers a certificate with chemical composition, decarburization,
degree of pureness, values of mechanical tests after heat treatment and Jominy band
Quality Acceptance: controls of the bars by sample
dimensional checks on the section (gauge)
straightness and flatness (steel rule)
chemical composition (quantum analysis)
Verifications during Process by sample
surface and section hardness after heat treatment (portable-durometer)
hooks welding penetration (macrograph)
notched-bar impact strength
Checks before painting 100%
dimensional checks (gauge, goniometer)
metal integrity (magnetoscope)
hooks position (gauge)
pair forks alignment (goniometer, steel rule)
The norms of reference define the fork acceptability parameters to obtain
Each new fork model put into production is submitted to the following tests:
1 fatigue test - 1,000,000 cycles with load 25% higher than normal (pulse test bench)
1 static test - 2 cycles with triple nominal load for 30 sec/each., without permanent deformation (pulse test bench)
1 check of the mechanical characteristics, with resilience of more than 27 Joules at T=-20°C